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Four multiples of 10 2017-09-23
From Laudacir:
Four multiples of 10 are added together.the total is a 3 digit number with three consecutive digits. What could the four number be?
Answered by Penny Nom.
Two digit numbers that contain 5 2017-08-11
From Irish:
How many two digit numbers contain the digit 5?
Answered by Penny Nom.
Significant digits 2017-08-06
From Pat:
The directions for a problem are: "Solve the problem, expressing your answer using the correct number of significant figures."

Problem 0.0043 divided by 2.04
Answer before using the correct number of significant figures is 0.002107843

Is the correct number of significant figures the number below?
2107843

Pat

Answered by Penny Nom.
A 4 digit safe combination 2017-07-29
From Donna:
I lost my safe combination :( it is 4 digit # with the last digit being 2. I do not think the 1st digit is 1, 2 or 3
Can u help? Thank u :)

Answered by Penny Nom.
Some 4 digit numbers 2017-07-24
From Camille:
I need all of the 4 digit combinations that starts with number 3 and digits can't be repeated
Answered by Penny Nom.
The smallest and largest 4 digit integers 2017-06-13
From Avneetpal:
Difference of the smallest and biggest 4-digit number
Answered by Penny Nom.
4 digit codes with repeating digits 2017-06-01
From Morgan:
what are all possible 4 digit code repeating numbers? cuz i know that you have one website on it but, it doesn't repeat 2 numbers in a code.
Answered by Harley.
A five digit number 2016-10-12
From Massa:
Explain why any four digit number is less than any five digit number?
Answered by Penny Nom.
Four digit numbers 2016-09-08
From ning:
0000-9999 there is ten thousand 4-digit numbers. How to find the number of ways that 4 digit are the same? How to prove it by using formula?
Answered by Penny Nom.
The tens digit of a number is five times the unit digit 2016-05-19
From sanjeev:
The tens digit of a number is five times the unit digit. Find the number?
Answered by Penny Nom.
A six digit code 2016-05-06
From Ralph:
How many combinations are possible if a "safe" has four buttons and you can use a six digit code? (these are just single press buttons..)For example, this could be one possible combination: Button 4 Button 1 Button 1 Button 3 Button 2 Button 4. Thanks!
Answered by Penny Nom.
The last two digits of a phone number 2016-04-03
From Joshua:
I want to find the last two digits of a phone number whose first eight numbers of a ten digit phone numbers are known.
Answered by Penny Nom.
A 2 digit number 2016-02-08
From Lloyd:
The sum of digits of a certain 2 digit number is 7. Reversing its digits increases the number by 9. Find the number
Answered by Penny Nom.
A three digit number 2015-11-13
From Tina:
The sum of the digits of a 3-digit odd number is 13. The digit in the tens place is 4 less than the digit in the hundreds place and 3 more than the ones digit. What is the number?
Answered by Penny Nom.
A two digit number 2015-08-21
From Cameron:
Write the 2 digit number that matches the clues.

My number has a tens digit that is 8 more than the ones digit. Zero is not one of my digits.

My number is ________.

Answered by Penny Nom.
A two digit number 2015-06-05
From Madison:
Trini took some photos. The number of photos she took is a two digit number. The sum of the digits is 11. The tens digit is 3 more than the ones digit. How many photos did Trini take?
Answered by Penny Nom.
The units digit of a prime 2015-01-08
From Patricia:
Every prime number greater than 10 has a digit in the ones place that is included in which set of numbers below 1 3 7 9 or 1 3 7 or 0 2 4 5 6 8 or 1 3 5 9
Answered by Walter Whiteley.
Missing digits in a phone number 2015-01-07
From Janelle:
I had a friend try and play a game on me, regarding phone numbers, so I only know the area code , and the last four digits of the phone number. Which means, there are 3 digits that I need to figure out all the possibilities to.
Answered by Penny Nom.
A second grade word problem 2014-09-09
From Beth:
How do I explain to my second grader how to find the answer to the problem:
My tens digit is 8 more than my ones digit. My ones digit can not be zero.

Answered by Penny Nom.
A secret number 2014-09-08
From jai:
it is smaller than half of 100, it is more than 4 tens and less than 5 tens, the tens digit is two more than the ones digit , together the digits have a sum of 6..... What is my secret number?
Answered by Penny Nom.
4821x14y is an 8-digit number divisible by 72 2014-08-06
From RAYA:
if 4821x14y is an 8-digit number divisible by 72. How many values can x and y take?
Answered by Penny Nom.
A six digit number 2014-06-30
From anupam:
hi,
my daughter asking a solution for the below question, kindly help.

Write the smallest 6 digit number wit digits ( 2,4,3,0,5,7).

plz this is an urgent requirement.

regards,
anupam

Answered by Penny Nom.
Three digit numbers 2014-05-15
From Mudassir:
how many 3 digits numbers which at least one digit is 2 ?
Answered by Penny Nom.
A 4 digit number 2014-04-04
From LIM:
"A" is a 4 digit number formed by all the numbers from 1 to 4. When "A" is divided by 9, the remainder is the biggest possible value. What is the biggest value of A?
Answered by Chris Fisher.
Four digit phone numbers 2014-02-25
From Tom:
Hi, I'm an online math teacher, working on lessons for my students.

This question is in their book and I can't do it...! Help!

It has to do with phone numbers, and in this problem, we are only dealing with the last 4 digits of the number.

It asks how many possible numbers we have if at least one digit repeats in the last 4 digits of the number.

Answered by Penny Nom.
A number with all the digits different 2014-02-07
From Jon:
I'm not a mathematician but just curious. Is there a name for a number of up to ten digits where each digit is different, i.e the equivalent of an isogram in linguistics? My online banking gives me a random 8-digit number each time I log on and it is rare to get one of the type I refer to. There must be calculable odds, but I'm only allowed one question!
Thanks in advance
Jon

Answered by Harley Weston.
Units digit 2014-01-03
From gracie:
9^23 units digit
Answered by Penny Nom.
A 4 digit number 2013-12-20
From swathi:
How many 4 digit numbers can be formed using the digit 3 only once but the digit 3 must be used in all numbers?
Answered by Penny Nom.
Two, 2-digit numbers 2013-09-24
From Tony:
Write a problem that has two 2-digit numbers.

solve your problem.

Answered by Penny Nom.
A two digit number 2013-09-04
From JEFFERSON:
The sum of the digits is 6. When the digits are interchange, the new number represented is 3 time the 10 digit of the original number. Find the original number?
Answered by Penny Nom.
Four digit combinations starting with 7 6 2013-05-15
From Kaye:
How do I find the rest of a four digit combination starting with 7 6?
Answered by Penny Nom.
A 2-digit number 2013-05-13
From A teacher:
Find a “2-digit number” where the sum of the 1st digit (on the Left) and the square of the 2nd digit equal the same number.
Answered by Lorraine Dame, Harley Weston.
A 4 digit code 2013-03-26
From chris:
I saw a previous question about a 4 digit code type thing and I was wondering if you could email me that same type of thing. I changed the pin number on my phone's lock screen and I tried hard to remember it, then I had to go help my mom with something and I automatically forgot it and there is no way for me to get back on my phone. I need all of the possible 4 digit number combinations without the numbers 0, 1, or 2. It cannot be repeating, ascending, or descending.
I know you may not want to do all of them, but I really need it.

Answered by Robert Dawson.
Six-digit passwords 2013-03-19
From Judy:
Hello:
Can you please explain why the answer to the following question is 10^6? What is the number of possible six-digit passwords when using the digits 0 through 9, with repetition allowed.
Thank you.

Answered by Penny Nom.
A 3 digit number puzzle 2013-03-11
From Bonnie:
My number has 3 digits. My number is not a multiple of 100. My number is a multiple of 50. My number is a factor of 1000. What is my number?
Answered by Penny Nom.
Four digit "combinations" using 0124 2013-02-27
From Ayana:
What are all the possible four digit combinations using 0124. Please list them for me. Thank you.
Answered by Penny Nom.
A 4 digit phone lock using the digits 4, 2, 3 and 0 2012-12-24
From Ragu:
I would like to know formula for searching a combination of 4 digit. eg.

I knew my Phone Lock combination is my car plate number 4230. But this time, i used another way around instead of 4230.

But I am sure, there is only this 4 digits only. 4 & 2 & 3 & 0

Answered by Penny Nom.
A valid UPC number 2012-12-22
From Jacob:
A valid UPC number , ABABABABAB- C must end in a 2 after using the rule:

3A +B+3A+B+3A+B+3A+B+3A+B+C=##2.

What would term C need to be in order to make the following UPC valid? 2741825293-C

Answered by Harley Weston.
The last 4 digits of a cell phone number 2012-12-22
From Jacob:
If the last 4 digits of a cell phone number, XXX-XXX-ABCD, are restricted where: A cannot be 0 or 1 and B cannot be 0 / how many possible 4 digit combinations are left?
Answered by Penny Nom.
Transposition error 2012-12-03
From Carol:
What is the correct term for when a child writes 61 instead of 16, or 83 for 38--when they switch the place values of a number?
Answered by Chris Fisher.
Some 4 digit numbers 2012-10-25
From samira:
How many 4-digit numbers are there in which the first and last digits are the same?
Answered by Penny Nom.
Some 6 digit numbers 2012-10-23
From Mason:
How many different 6 digit numbers can you make using the digits 1 ,2 5, 6, 7, and 9? How many of these six-digit numbers are divisible by 6?
Answered by Penny Nom.
4 digit combinations 2012-10-17
From Scott:
How many different 4- number combinations from 0-1-2-3-4-5-6-7-8-9 with 2 out of the 4 odd and 2 out of the 4 even, with no numbers repeating. Thanks
Answered by p.
A four digit number 2012-10-09
From cyndi:
find this 4 digit number: the tens digit is 1/3 of the hundreds digit; the 2 digit number formed by the tens and ones digits i the largest prime number smaller than 40; the sum of all 4 digits is the same as the number of face on an icosahedron ? what is the number?
Answered by Penny Nom.
The units digit 2012-09-11
From Shaunice:
Simplify each of the following expressions and determine what the last digit would be. a. (24^15) 4
Answered by Penny Nom.
Six digit numbers 2012-09-11
From Fiona:
using the numerals 0, 2, 3, 5, 7, 9, make as many six-digit numbers as you can. Rearrange them into ascending order
Answered by Robert Dawson.
A 2-digit number 2012-08-23
From patty:
Write the 2-digit number that matches the clues. My number has a tens digit that is 8 more than the ones digit. Zero is not one of my digits. My number is
Answered by Penny Nom.
A 4 digit number 2012-08-09
From May:
The number is given as ABCD. The first digit is a quarter of the last digit. The second digit is one less than the first digit. When the number ABCD is multiplied by four its digits appear in the reverse order. None of the digits are the same. What is the number. Pleas help because my child need help and I can not do this. Thank you.
Answered by Penny Nom.
Mr. Schneider's mass 2012-02-29
From Khiya:
Mr. Schneider's mass is 2 digits. The first digit is 3 times the second digit. Both digits are odd numbers, and his mass is greater than 35 kg. What is Mr. Schneider's mass?
Answered by Penny Nom.
Four digit combinations from 1,2, ..., 9 2012-02-26
From Errol:
show me a list with all four digit combination numbers from 0 -9
Answered by Penny Nom.
Can the result of the calculation be 2? 2012-02-09
From Thomas:
You have the digits 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9 in a random order side by side and put randomly between two digits a colon, so that a division comes into existence. Can the result of the calculation be 2?
Answered by Robert Dawson and Chris Fisher.
A two digit number 2012-01-29
From Christine:
Five times the sum of the digits of a two digit number equals the number. If the digits are reversed, it becomes nine more than the original number. What is the original number? I really don't understand this question, help me please
Answered by Penny Nom.
The number of digits in a number base m 2011-12-22
From Jash:
Assume there is a number system of base m.

The one property of this system is: If 2 numbers written in this system, which have 'a' and 'b' as the number of digits are multiplied, then the product of the 2 numbers will have a number of digits which is a function f(a,b).

In other words, as long as the number of digits of the 2 numbers are constant, the number of digits of their product is a constant.

Find m.

Answered by Robert Dawson.
Rounding 2011-12-14
From seth:
A decimal number rounded changed to 23.7 after it was rounded. Give a decimal number that is less than 23.7 and another that is greater than 23.7 that each round to 23.7. Explain to what place each number was rounded.
Answered by Penny Nom.
The units digit of a prime number 2011-11-22
From Mike:
Every prime number larger than 10 has a digit in the ones place that is included in which set of numbers below?
A. 1,3,7,9
B. 1,3,5,9
C. 0,2,4,5,6,8
D. 1,3,7

Answered by Penny Nom.
3-digit, daily numbers 2011-09-29
From Margaret:
I need the list/group for a raffle that would contain the combinations for a 3 digit (000-999) daily number. There would be 100 tickets sold with 10 3-digit numbers from each numerical group beginning from 000's, 100's 200's, 300's,...900's. No duplicates/replacement. What would be the list of possible combinations of each group of 100 tickets, keeping each different group/list of combinations in separate blocks of 100 tickets without duplication. So I could use 1 list of 100 this year and the next list of combos next year and so forth. Please help!

Example: 000,197,245,367,445,569,618,777,842,964

What would be the possible lists of each 100 tickets? Thank you

Answered by Penny Nom.
A number less than 100 2011-09-17
From Sharon:
I am a number less than 100. My ones digit is 6 the sum of my digit is 11. What sum am I?
Answered by p.
A four digit number 2011-09-16
From gina:
i am having a hard time figuring this out.. i believe the answer is 3105 but the 0 is throwing me off... i am a 4 digit number between 3100 and 3200, none of my digits are even, the sum of my digits is 9, the largest digit is in the ones place, what number am i ??
Answered by Penny Nom.
A two digit number 2011-08-26
From Felicia:
Write the 2-digit number that matches the clues.
My number has a tens digit that is 8 more than the ones digit.
Zero is not one of my digits

Answered by Penny Nom.
Numbers with a digit 9 2011-05-13
From Veronica:
How many numbers between 200 and 750 have a 9 for at least one of the digits?
Answered by Penny Nom.
5 digit numbers using the digits 5 and 2 2011-04-27
From sissy:
I need a list of all possible 5 digit combinations using 5 and 2 numbers can repeat
Answered by Penny Nom.
A two digit number 2011-03-01
From jhoanna:
the sum of the digits of a two digit number is 10. The value of the number is 16 times the units digit.Find the number.
Answered by Penny Nom.
What is the 6001st digit that Sam wrote? 2011-02-15
From Sarah:
Sam wrote the natural numbers from 1 to 5280 in order. What is the 6001st digit that Sam wrote?
Answered by Penny Nom.
Reversing the digits 2011-02-08
From rejie:
if the digits are reverse , the number is 9 less than the original number.what is the equation?
Answered by Penny Nom.
An even multiple of 27 2011-02-01
From parth:
the 6 digit # 63x904 is an even multiple of 27 what is X
Answered by Penny Nom.
Four digits are to be randomly selected 2011-01-20
From sarahbear:
Suppose four digits are to be randomly selected (repetitions allowed) Find the probability that
A. 5562 is selected
B.0000 is selected
C. All four digits are the same
D. 2 is the first digit selected

Answered by Penny Nom.
A product of 1 000 000 2010-11-19
From Sharron:
There are many pairs of numbers that when multiplied together give a product of 1 000 000. However, there is one pair, and only one pair, of whole numbers that contain no zero digits and has a product of 1 000 000. What are these two numbers?
Answered by Stephen La Rocque.
A six digit number containing no zeros 2010-11-15
From John:
Find a Six digit number containing no zeros in which the first digit is three less than the third, the third digit is three less than the fifth,and the second digit equals the sum of the last three digits.
Answered by Penny Nom.
What numbers can I be? 2010-11-13
From john:
my thousands digit is 2 times my ones digit.my hundreds digit is my ones digit plus 2. my tens digit is the difference between my thousands and hundreds digit what numbers can i be?
Answered by Penny Nom.
Four-digit numbers using 0,3,4,5,6,and 7 2010-11-12
From Katy:
Using only the digits 0,3,4,5,6,and 7, how many distinct four-digit numbers exist that are greater than 4002 and less than 6732?
Answered by Stephen La Rocque.
A three digit number 2010-09-22
From Andrew:
Both the sum and the product of its three digits are 6. The least digit is in the hundreds place and the greatest digit is in the ones place. Write it in word form:
Answered by Penny Nom.
Choose any three digits that are less than ten 2010-09-12
From cecille:
my son have a homework, but i don't understand the question. here's the problem:
choose any three digits that are less than ten.
make all the two digit number you can using those three digits.
add up the two digit numbers you created and divided by the sum of the original three digits.
record your answer. then do it again with another three digits. write your observation about the answer.

Answered by Claude Tardif.
Numbers that can be formed using the digits 1,2,3,4,5,8,9 2010-07-19
From Donessa:
write the number that is 2000 more than the difference between the largest and the smallest number that can be formed using the digits 1,2,3,4,5,8,9
Answered by Tyler Wood.
Two problems 2010-05-27
From debbie:

Question from debbie, a parent:

hi, i have a daughter and she asked me a maths question I cannot solve. I was just wondering if you can give me the answers plus the working out so I could explain to my daughter,

1. The leftmost digit of a six-digit number N is 1. If this digit is removed and then written as a rightmost digit, the number thus obtained is three times N .Find N.

2. Four friends are racing together down a flight of stairs. A goes 2 steps at a time, B 3 steps at a time. C 4 steps at a time and D 5 steps at a time. The only steps which all four tread on are the top one and the bottom one. How many stairs in the flight were stepped on exactly once?


Answered by Penny Nom.
Four digit numbers 2010-05-22
From tyeisha:
Whats all the four digit numbers you can come up with using numbers 0-9
Answered by Tyler Wood.
Odd numbers with no repeated digits 2010-05-01
From jameka:
How many odd numbers can be written from the set {2,3,4,5,6} if no digits may be used more than once?
Answered by Penny Nom.
A three digit entry code 2010-04-14
From Bryon:
The entry code for the executive bathroom is a three-digit odd number with no repeated digits. If you want to try to break in, what is the maximum number of numbers you'll have to try? (Remember that the three-digit numbers cannot start with zero.)
Answered by Stephen La Rocque and Penny Nom.
How many zeros? 2010-03-18
From jeff:
1 light yr is 6,500 billion miles, the galaxy "Andromeda" is 2,500,000 million light yrs, how many zeros are in this equation ?
Answered by Robert Dawson.
A code on my pedometer 2010-02-19
From Jacqui:
Hi I need to break a code on my pedometer. I have only 3 digits 1 2 and 3 but need to fill a 5 digit code. I have tried to find answers but they seem to relate to if the digits are only used once. I can use them in any order and repeated as many times. How many possibilities are there and is there an easy way to run through them. Many thanks
Answered by Tyler Wood.
4-digit positive numbers 2010-02-15
From marjon:
Find the sum of all the 4-digit positive numbers with no zero digit.
Answered by Penny Nom.
Three digit odd numbers 2010-02-04
From Rebecca:
Question from rebecca, a student:

how many three digit odd numbers can be formed using the digits 1,2,3,4,5,6 without using any digit more than once?

Answered by Tyler Wood.
A 4-digit phone code 2010-01-21
From pat:
my daughter can`t remember her 4-digit code to unlock her phone. she is pretty sure it starts with a 4. can you help us? my brain is locked up
Answered by Robert Dawson.
Four digit numbers with no repeats 2010-01-02
From Daniel:
I want to know how many different numbers there would be between the numbers 0000-9999 that do not have any numbers that duplicate or repeat in the number? For example the first number would have to be 0123 and the last would be 9876 (I think) Thanks!
Answered by Penny Nom.
A 4 digit number 2009-12-15
From Lisa:
Billy Club was assigned the task of putting numbers on all the playground balls used during daily recess. Billy will number the balls using the following rules:

1. It will be a 4-digit number.

2. The digit in the thousands place will be a 1 or a 2.

3. The digit in the hundreds place will be a 2, 4, or 6.

4. The digit in the tens place will be an odd number.

5. The digit in the ones place will be greater than six.

How many balls can Billy number if he follows these rules?

Answered by Robert Dawson.
Three digit numbers 2009-12-11
From christopher:
i need a list of all 3 digit combinations with repeat of a number thnx
Answered by Penny Nom.
Two digit numbers 2009-12-10
From Jim:
Can you tell me how many 2 digit numbers can be created from the following:

1118539

Answered by Penny Nom.
A place value problem 2009-11-29
From Ivy:
My tens digit is 4 less than my thousands digit. My ones digit is twice my tens digit. My ten thousands digit is one less than my ones digit. My hundreds digit is the sum of my tens and thousands digit. My thousands digit is 6.
Answered by Penny Nom.
Jill and Bill 2009-11-04
From Lisa:
Jill and Bill are two members of the Hill family. Jill is 8 years old and Bill is 9 years old. What will Bill's age be when the total of the digits in both their ages is once again 17?
Answered by Stephen La Rocque.
In what order are the following digits? 2009-09-30
From Jewell:
In what order are the following digits? 0,2,3,6,7,1,9,4,5,8
Answered by Penny Nom and Claude Tardif.
Cubes and squares 2009-09-16
From Stanley:
What is a three consecutive digit number like 5,6,7 , which is two less than a cube and two more than a square?
Answered by Robert Dawson.
A three digit number 2009-09-04
From Mark:
How many 3 digit positive integers are odd and do not contain the digit 5?
Answered by Penny Nom.
A four-digit positive integer 2009-09-04
From TRACEY:
I AM A FOUR-DIGIT POSITIVE INTEGER SUCH THAT THE SUM OF MY DIGITS IS 18 AND MY DIGITS REVERSED ARE EXACTLY FOUR TIMES GREATER THAN MYSELF. WHAT NUMBER AM I?
Answered by Robert Dawson.
The sum of digits of 4444^4444 2009-08-31
From SHIVDEEP:
The sum of digits of 4444^4444 is A .The sum of digits of A is B .
Find the sum of digits of B ?

Answered by Claude Tardif.
Unlocking my suitcase 2009-08-21
From Jamboree:
I need to have all the possible combination of three digit between 0-9, i have seen the answer that there are 720 combination are there. Could you please show me all those combination numbers so that i could try it out to unlock my suitcase, will you please write it down all those combination and send it to me
Answered by Victoria West.
Units digit 2009-07-23
From Jyll:
How do solve for the units digit? And that, what is the units digit of the first 1000 prime numbers?
Answered by Robert Dawson.
Two questions from math class 2009-06-18
From Con:
Hello,

My name is Con and my son is required to answer the following questions for his maths class.

He has attempted Q1 through trial and error and has found the answer to 72453. Is this correct?

He has attempted to draw the triangles described in Q2 in a number of ways and has found that BE can not equal ED and is dependent of angle BAC. Therefore, he claims that the triangle can not be drawn/practical. Is this correct or is there a slolution?

Q1.
Digits 2, 3, 4, 5 and 7 are each used once to compose a 5-digit number abcde such that 4 divides a 3-digit number abc, 5 divides a 3-digit number bcd and 3 divides a 3-digit number cde. Find the 5-digit number abcde.

Q2.
Let ABC be a triangle with AB=AC. D is a point on AC such that BC=BD. E is a point on AB such that BE = ED = AD. Find the size of the angle EAD. Con

Answered by Chris Fisher.
The smallest 4 digit number 2009-06-17
From Kat:
What is the smallest 4 digit number? 0001 or 1000
Answered by Robert Dawson.
The last non cero digit of a factorial 2009-06-12
From Wilson:
How can I find the last non cero digit from a factorial calculation of a big number. For example 10! = 3628800, the last non cero digit is 8. What is the last non cero digit of 10! ??
Answered by Robert Dawson.
A number puzzle 2009-05-17
From Gita:
Ok, we really need help for a homework problem due on Monday morning
I've been trying for 2 hours and can't figure it out---if I can't I'm not sure
how my son can....We've been given a puzzle with the following rules:
--The sum of each side must equal 15
--We can only use the numbers 1,2,3,4,5,6,7, 8
--A number can be used only once
(Hint: Think of all combinations of 3 numbers = 15)
--The puzzle looks like this:

_____ _______ ______

_____               ______

_____ _______ ______


Answered by Penny Nom.
7 digit combinations 2009-05-11
From CAROL:
I NEED TO KNOW HOW MANY 7 DIGIT COMBINATIONS FROM 0-9 THERE ARE WITHOUT ANY REPEATES, OR WHAT THOSE COMBINATIONS ARE?
Answered by Penny Nom.
Combinations and permutations 2009-05-07
From Renee:
We are trying to figure out the equation or how to solve the problem of how many combinations of 4 digits you can get out of 0-9 without repeating the numbers in a set (i.e., no 0001, 0002) begining with 0123, 0124, 0125 etc Thanks!
Answered by Stephen La Rocque.
Four-digit combinations 2009-04-18
From Carri:
How many 4-digit combinations can be made out of digits 1, 2, 3, 4, & 5 using each number once? What are the combinations?
Answered by Penny Nom.
What is the original number? 2009-04-16
From Yueh:
A five digit number is written on a blackboard. Ron erases one of the digits and adds a newly constructed number to the original one. The result is 41751. What is the original number?
Answered by Claude Tardif.
Units digit 2009-04-15
From A student:
What is the unit digit of 47 to the 43rd power? Please answer as soon as possible. Thank you.
Answered by Stephen La Rocque.
Four-digit numbers 2009-04-11
From jp:
How many four-digit numbers are there?
Answered by Penny Nom.
How many times is 9 in pi? 2009-04-09
From Serena:
How many times is 9 in pi?
Answered by Robert Dawson.
A 5 digit push combination lock 2009-04-04
From Andrew:
I have a 5 digit push combo lock that i forgot the combo for. it has numbers 1-4 and each number can be pressed more then once ie. 11111, 36356 is there an algorithm out there that will list out the possible combinations for me? or maybe a way i could write them out myself.
Answered by Penny Nom.
0123456789 2009-03-25
From Dr.:
Many years ago I discovered that there are 33 numbers which, when multiplied by 0123456789, simply rearrange the digits. Surprisingly (to me at least) is the fact that the digits of all of those 33 numbers add up to one of the 6 "cardinal" numbers 1, 2, 4, 5, 7, and 8. For example 6 + 2 = 8 and 62 X 0123456789 = 7654320918 etc.
Another interesting (to me) fact is that only the cardinal numbers 1, 2, 4, 5, 7, and 8 rearrange the digits in the number 9876543210.
My question is: "Is this known to anyone but me and the people I have told?"

Answered by Robert Dawson.
Choosing a 4 digit number at random 2009-03-24
From shabkhal:
If a four-digit number is chosen at random, what is the probability that the product of the digits is 12.
Answered by Harley Weston.
The units digit of 2^95 2009-03-18
From Sharvon:
what is the units digit of 2^95
Answered by Robert Dawson.
4 digit numbers from 1159 2009-03-10
From David:
I have the digits "1159" and need to come up with a complete list of possible four-digit combinations. It does NOT matter the order of the two number ones (1), so this will help eliminate many possibilities.

Separately, it would also help to actually know the actual number of combinations with which I am dealing to start.

David :)

Answered by Penny Nom.
Four digit numbers 2009-03-10
From Theresa:
I need to know the number of 4 digit numbers that can be formed using 1-2-3-4 without repeating numbers
Answered by Penny Nom.
4 digit strings starting with 7 2009-03-03
From Angel:
I need to no all the 4 digit combinations starting with 7 and with no repititions.
Answered by Penny Nom.
A four digit number 2009-02-12
From alex:
the number of tens plus the number of hundreds equals the number of thousands. the number of ones is half the number of tens and one more than the number of hundreds the hundreds digit is 2. what is this four digit number
Answered by Penny Nom.
The page numbers in a book 2009-02-10
From Nichole:
It takes 852 digits to number the pages of a book consecutively. How many pages are there?
Answered by Penny Nom.
Dividing the digits 1 - 9 into two groups 2009-02-09
From donna:
using the numbers 1 to 9 can you arrange these into 2 groups, both of which have the same total, and no you cant turn the 6 upside down
Answered by Penny Nom.
4 digit arrangements of 7 3 6 6 2009-02-05
From Carole:
I need all the four digit combinations using the numbers 7 3 6 6
Answered by Penny Nom.
The units digit is 5 2009-02-02
From Ray:
the number that when squared the units digit is 5
Answered by Penny Nom.
Missing three digits in a phone number 2009-01-30
From Elmer:
I have part of a phone number. the first 3 digits are 212, the last digit is four, and the three missing digits are all odd, how many numbers will I have to call to get the right number?

212- _ _ _ 4?

Answered by Stephen La Rocque and Penny Nom.
Four digit numbers using 1, 0, 2 and 8 2009-01-27
From Mike:
How many combinations of this four digit number 1028 can this produce only using those numbers. Example would be 0000, 0001,0002,0008,0010,0011,0012,0018,etc...
Answered by Penny Nom.
Three consecutive natural numbers 2009-01-26
From abby:
1.what is the smallest four-digit number that is the sum of the three consecutive natural numbers? what are the three consecutive natural numbers that give this sum?

2.what is the largest three digit number whose square root is a prime?

Answered by Penny Nom.
The tens digit of 0! + 1! + 2! + 3! + 4! .............+9999! + 10000! 2009-01-23
From Kaylyn:
determine the tens digit for the expression:
0! + 1! + 2! + 3! + 4! .............+9999! + 10000!

Answered by Robert Dawson and Penny Nom.
5 "digit" combinations 2009-01-22
From Timothy:
I was wondering how many different 5 digit combinations are possible using 0-9 and a-z and you can use the same letter or number repeatedly in the combination.
Answered by Penny Nom.
A three digit number 2009-01-20
From marcha:
when this three digit number is rounded to the nearest ten, the sum of its digits is 16 the hundreds digit of this number is 8 and the ones digit is 5, what is the number?
Answered by Robert Dawson.
A four digit passcode 2009-01-12
From john:
i have a machine at home that has a four digit passcode and the numbers range from 1 to 4 how can i get all the ways those numbers can be used
Answered by Harley Weston.
A 4-digit number 2009-01-05
From Anya:
It is a 4-digit number

The tens are double the ones.

The thousands are double the tens.

The sum of the digits is 19.

What number is it?

Answered by Penny Nom.
The 2 rightmost digits 2008-12-18
From Peter:
Is there a pattern for the 2 rightmost digits of a power? For example, one problem for a math competition was what are the 2 rightmost digits of 3^1993?
Answered by Robert Dawson and Victoria West.
Student who is inverting digits 2008-12-09
From Tammie:
Do you have any strategies for addressing inversion of digits in two digit numbers. For example - The student the teacher is working with will write "14" and the number is 41. She has tried highlighting, practice writing numbers, and hundreds charts and finding patterns. Help! Thank you!
Answered by Robert Dawson and Victoria West.
Three one-digit numbers 2008-12-06
From JOANNA:
Could you please tell me what Adding Three One-Digit Numbers += 15 1-9 without using any number twice
Answered by Penny Nom.
I am a whole number less than 100 2008-12-03
From Cecelia:
If I am a whole number less than 100
and the sum of my digits is 4
and half of me is an odd number
What number am I?
Also am I prime or composite?

Answered by Penny.
Three digit combinations 2008-11-12
From Jimmy:
How many 3 digit combinations are possible using numbers 1-9? How did you get that answer?
Answered by Harley Weston.
A 4 digit number 2008-11-06
From Chris:
numbers 0 - 9 form a 4 digit number with no repetition.

It would round to 3000 if rounded to the nearest thousand

The digit in the tens place is twice the value of the digit in the thousands place.

It is an odd number.

It contains the largest digit.

It contains one digit less than 2.

The digit in the hundreds place is odd.

Can you find the 2 numbers?

Answered by Penny Nom.
4 digit combinations 2008-11-05
From Laura:
I need to know all the number combinations possible with a 4 digit combination with double zero in the middle???
Answered by Penny Nom.
What is the exact value of pi? 2008-09-27
From mahesh:
what is the exact value of pi.
22/7 is accurate value of pi, if not then how can i find out the exact pi value.

Answered by Harley Weston.
Repeating fractions 2008-09-09
From Juli:
My teacher recently put my math class to the test... We were deiscussing repeating fractions and she asked us to find out what the bar over a repeating decimal is called. I found out it was called the vinculum. But she also said to find out what the number under the vinculum was called. I can't seem to find it anywhere.
Answered by Penny Nom.
Hundreds, tens, and units digits 2008-09-05
From Cynthia:
write an expression for the value of a three-digit number whos hundreds, tens, and units digits are x, y, and z, respectively
Answered by Penny Nom.
3 digit combinatios from 0-9 2008-07-27
From Mike:
I need to know all the possible 3 digit combinations using the numbers 0-9. The numbers can be repeated as long as they are not of the same set. Example for not repeating: 123 is ok but not 321 or 231,132,213, etc. Please help me. Thanks, Mike.
Answered by Stephen La Rocque.
The product of the digits of a four digit number 2008-07-26
From Pete:
I am a student preparing for a competition and this was one of the prep problems: The product of the digits of a four digit number is 6x5x4x3x2x1. how many such numbers are there with this property?
Answered by Stephen La Rocque.
Sum of Digits 2008-07-24
From Warren:
If 100^25-25 is written in decimal notation, what is the sum of digits?
Answered by Penny Nom.
The number of digits in a really big exponent 2008-07-21
From Pete:
how would you find the number of digits in a really big exponent without a calculator?
Answered by Penny Nom.
The units digit of (7*3)^21 2008-07-16
From surender:
what will be the unit digit of (7*3)^21?plz give me method 2 calculate such problems.thank you.
Answered by Penny Nom.
Smallest Even Number 2008-07-09
From Ma.:
Using the digits 0, 1, 3, 4, and 5 only once give the smallest 5-digit even number
Answered by Janice Cotcher.
Zip codes, postal codes and 5 digit codes 2008-07-08
From Mike:
Sorry if you have answered this before but I don't understand the explanations I have seen. How many possible combinations are in a 5 digit code (like a Zip Code). Is there an equation that can be used for this type of question?
Answered by Penny Nom.
Probability and two digit numbers 2008-07-07
From Peter:
What is the probability that if you multiply two randomly selected two digit whole numbers, the result is greater that 100 and less than 200. Express your answer as a common fraction.
Answered by Janice Cotcher.
Units digit 2008-07-02
From seemachauhan:
How to find unit digit of various numbers and what are unit digits?
Answered by Penny Nom.
The sum of the digits of two-digit number is 9 2008-07-01
From Audrey:
the sum of the digits of two-digit number is 9. if the digits are reversed, the new number if 63 greater than the original number. find the number.
Answered by Penny Nom.
A 7-digit odd number 2008-06-26
From Godryk:
I am the smallest 7-digit odd number. my ones digit is the sum of my thousands, and ten thousands digits. What number am I?
Answered by Penny Nom.
111...111 * 2003 2008-06-23
From Peggy:
Number a = 111...111 formed by 2003 1's. Find the sum of the digits of the number 2003 * a.
Answered by Penny Nom.
Four digit combinations 2008-06-23
From star:
Can you you give me a list of all 4 digit combination starting with the number 7, for example 7123,7213.
Answered by Penny Nom.
The sum of the digits of a number 2008-06-23
From Ben:
Question: Using mathematical induction, prove that if the sum of the digits of a number is divisible by three, then the number itself is also divisible by 3.
Answered by Penny Nom.
Nine digit numbers 2008-05-21
From Alex:
List of Nine digit numbers, that can be divided by nine?
Answered by Janice Cotcher.
A 6 digit number 2008-04-23
From rajiv:
write the smallest 6-digit number using three different digits with 6 in the ten thousands place and 1 in the hundreds place
Answered by Penny Nom.
The sum of some 5 digit numbers 2008-04-05
From Tom:
There are 120 five-digit numbers that use all the digits 1 through 5 exactly once. What is the sum of these 120 numbers?
Answered by Penny Nom.
Rearrangements of the digits in 0123456789 2008-03-23
From Joe:
Found a close problem but not quite. Using digits 0123456789, how can I figure what all the different possibilities would be without repeating any digits? I know that there are 10! possible answers but how can I figure out what they are?
Answered by Stephen La Rocque.
A number puzzle 2008-03-22
From Cassidy:
1. Number has three digits
2. The second digit is an odd number
3. The first and third digits are even numbers
4. The number can be divided by five, six, and seven with a remainder of four.

How do you even start this type of problem?

Answered by Victoria West.
Some three-digit numbers 2008-03-05
From Toni:
The following is a word pattern problem listed on my son's homework: write a set of three-digit numbers that contain one odd number and three even numbers. This confused the both of us because that would make his number a four digit number, right? please respond. Thanks.
Answered by Penny Nom.
A 4 digit passcode 2008-02-16
From Rob:
If there is a 4 digit passcode with only 6 punch in symbols, how many possibilities are there and what are they? symbols are: Y, X, RB, RT, LB, LT. Please get back to me, thanks for your time and help.
Answered by Stephen La Rocque.
Five digit combinations 2008-02-15
From Debbie:
I would like to get a list of all the possible 5 digit combinations of the numbers 12345.
Answered by Penny Nom.
A 2 digit number 2008-02-13
From Jenny:
The units digit of a certain two-digit number is one more than 4 times the tens digit. The number formed by interchanging the digits is 6 more than 3 times the original number. Find the original number.
Answered by Penny Nom.
I am a 4-digit number 2008-02-12
From Nickie:
I am a 4-digit number with no repeating digits. I am divisible by 5, my first two digits (left to right) make a number divisible by 3, and my first three digits make a number divisible by 4. Also, my digits have a sum of 19 and I have the digit 7 in the thousands place. Who am I?
Answered by Penny Nom.
A briefcase lock 2008-02-11
From Alfred:
A briefcase lock has 3 columns of numbers each 0-9. It opens with the correct combination of three numbers. How many combinations are possible to open the lock.
Answered by Penny Nom.
7, 6, 5, 4, 3 and 2 digit numbers 2008-02-10
From Edward:
using the number 12345678 how many 7, 6,5,4,3 & 2 digit numbers can you make when not using any number twice in the same number
Answered by Penny Nom.
Four digit numbers containing 85 2008-02-06
From Vonda:
How many four digit numbers contain the digit pattern 85 at least once and only once?
Answered by Stephen La Rocque.
A positive integer with 2007 digits 2008-02-06
From Tom:
Prove that there's a unique positive integer of 2007 digits lenght, divisible by 2^2007, and made up solely by the digits 2 and 5.
Answered by Penny Nom.
A 3 digit number 2008-01-23
From Adrian:
Consider a 3-digit number,abc,where a is not equal to c.Switch it so that it becomes cba.Subtract the lesser from the greater to obtain rst.Switch this so that it is tsr.Prove that rst+tsr=1089
Answered by Stephen La Rocque.
Units digit 2008-01-11
From Robin:
hello - my question is: what is the units digit of (13) to 4; (17) to 2 and (29) to 3 [(13)4(17)2(29)3]

(possible answers: 9 or 7 or 5 or 3 or 1)

Answered by Penny Nom.
A 3 digit number 2007-12-13
From Kim:
Find the number from the following clues:

A) is is a 3 digit even whole # divisible by 5
B} Each digit is different
C) Its hundreds digit is greater than its tens digit
D) It is less that 400, divisible by 3, and has only 1 odd digit.

Answered by Penny Nom.
A math riddle 2007-11-27
From Kathleen:
My 4th grade daughter was given a math riddle which she is expected to answer using a problem solving strategy. The question is:

The number of my hundreds and the number of my thousands is 3. The number of my tens is 7 times the number of my thousands. All my digits are different. What am I?

I have tried to come up with an answer, but am beginning to think it is less complicated than what I have come up with.

Answered by Stephen La Rocque.
How many marshmallows did I use? 2007-11-21
From gloria:
the # of marshmallows i use is an even # .it is 2 digit number more than 10 less than 20 the 10th digit half of one digit.how many marshmallows did I use?
Answered by Chris Langdon.
Using the digits 1 to 9 2007-11-20
From sunjoo:
write the least whole number that uses the digits 1 though 9 once each. explain your answer.
Answered by Penny Nom.
A ten digit number 2007-11-11
From jeff:
find the greatest ten-digit positive multiple of 12 using each digit once and only once
Answered by Penny Nom.
The sum of the digits of a whole number is 200 2007-11-06
From Kristin:
If te sum of the digits of a whole number is 200, the whole number may not have ________ digits?
Answered by Penny Nom.
The sum of the ones 2007-10-29
From Hangsun:
When 2 two digit numbers are added what is the greatest possible sum of the ones?
Answered by Penny Nom.
Some four digit combinations 2007-10-25
From Larisa:
Please tell me the answer or how to get the answer of every possible digit combination of 5173, for instance1735, 1753, 1573, 1537, 1357, 1375, etc.
Answered by Stephen La Rocque.
Show that there is no five-digit number which 2007-10-04
From Greg:
show that there is no five-digit number which uses each of the digits 1,2,3,4,5 such that the numbers formed by the first digit is divisible by 1, by the first two digits is divisible by 2 by the first three digits is divisible by 3, by the first four digits is divisible by 4, by the first five digits is divisible by 5
Answered by Stephen La Rocque, Claude Tradif and Victoria West.
Finding the last non-zero digits of large factorials 2007-10-04
From Mukesh:
i have to find last five non zero digits of integer which can be very large ( upto 10^12) . i can find last non zero digit of of any factorial. Now my problem is that i have to find last five non zero digit of factorial and also i want to general method for last K non zero digits of factorial n. For example 10!=3628800 so last non zero digit is 8 ,last two non zero digit is 88 .....and last five non zero digit is 36288.
Answered by Victoria West.
I have a 6 digits 2007-09-28
From Kim:
I have a 6 digits. My hundred-thousands digit is 1 less that my ones digit, 8 more than my thousands digit, twice my tens digit, and 4 times my hundreds digit. My ten-thousands digit is 0. What number am I?
Answered by Stephen La Rocque.
Four digit odd numbers 2007-09-26
From sonia:
how many 4 digit odd numbers can be made using the digits 2, 5, 7, and 8
Answered by Penny Nom.
The largest 4-digit odd number 2007-09-21
From Courtney:
what is the largest 4-digit odd number you can make with 1 - 9. You can not repeat digits within a number
Answered by Harley Weston.
Three digit numbers where all digits are even 2007-09-14
From Cielo:
Hannah made a list of all of the three digit whole numbers where all three digit were even. How many three digit whole numbers were on Hannah's list?
Answered by Penny Nom.
How many two digit numbers contain at least one 7? 2007-09-06
From Janet:
How many two digit numbers contain at least one number seven?
Answered by Penny Nom.
Four digit combinations 2007-09-04
From Natalie:
Using The Numbers 7 4 5

How many different 4-digit combinations are possible, you can use any of the numbers twice.

Answered by Penny Nom.
The digital lock for a cell phone 2007-08-29
From Hollie:
i have a four digit lock code on my cell phone and cannot remember what it is. i know that it does not contain a 2 or a 4 and none of the numbers are repeated. the numbers range from 0 to nine and the only way to figure out what the code is, is to try randomly. I was wondering if you could give me a list of possible combinations using the information i gave you to make it easier to crack the code.
Answered by Penny Nom.
A question about integers 2007-08-24
From Jerry:
Does there exist a positive integer such that when it is written in base 10 and its leftmost digit is crossed out, the new number is 56 times less than the original number?
Answered by Stephen La Rocque and Penny Nom.
How many three button codes are possible? 2007-08-23
From kim:
A home security device has ten buttons and is disarmed by pushing three buttons in sequence. How many three button codes are possible if each button can be pushed more than once in the code?
Answered by Stephen la Rocque.
The tens digit 2007-08-21
From Arul:
Hi.. Please help me on this question.. Sequence 2, 7, 22,…after the first three terms, each term is three times the previous term plus 1, a(n+1)=3an + 1. What is the sum of tens digit 33rd and tens digit of the 35 term?
Answered by Penny Nom.
The units digit of 23^45 + 67^89 2007-08-16
From Christopher:
What is the units digit of 23 to the 45th power plus 67 to the 89th power?
Answered by Stephen La Rocque.
who am i? 2007-08-08
From Phillip:
if you hold a mirror horizontally across my middle, i look the same in the mirror.if you hold a mirror between my second and third digits,i look the same in the mirror if you turn me upside down, i look the same. what 6 four-digit numbers could i be?
Answered by Penny Nom.
4 digit number combinations that start with the digit 2 2007-08-05
From tonnie:
my question is what are all the 4 digit number combinations that start with the number 2?
Answered by Harley Weston.
Four digit numbers 2007-07-30
From Spence:
My son has a problem that he has been unable to figure out. I was asked to try, but I am confused on how to get the last two parts. Any help would be great.
Thanks
Spence

How many four-digit numbers can be formed under each condition?

A) The leading digit cannot be zero: 9(10)(10)(10)=9000

B) The leading digit cannot be zero and no repetition of digits allowed: 9(9)(8)(7)=4536

C) The leading difit cannot be zero and the number must be less than 5000: ??

D) The leading digit cannot be zero and the number must be even: ??

Answered by Penny Nom.
The smallest 5-digit even number 2007-06-26
From charles:
Using the digits 0,1,2,3,4 and 5 only once give the smallest 5-digit even number
Answered by Penny Nom.
All 4 digit combinations for numbers 0 through 9 2007-06-21
From Jessica:
How can I find all 4 digit combinations for numbers 0 through 9?
Answered by Penny Nom.
A 5 digit key 2007-05-31
From Michael:
I have a 5 digit key pad lock on my truck. I want to print out all of the combinations to try. pad one=0 pad two =1 pad three=2 pad four=3 pad five =4. can you help me find and print all combinations?
Answered by Harley Weston.
How many ways can I choose 4 numbers from 10? 2007-05-10
From Mitch:
Can you give me a list of all possible four digit combinations using 0 to 9 no repeat numbers and the numbers do not have to be entered in a special order. If you could also show me how to calulate this it would be great
Answered by Stephen La Rocque.
Who am I? 2007-04-24
From Lisa:
I am the largest two digit number whose units digit divides its tens digit evenly. Who am I?
Answered by Stephen La Rocque.
24 four-digit numbers 2007-04-21
From Megon:
Of the 24 four-digit numbers formed from the digits 1,2,3,&4 is there an easier way to find their sum other than writing them all out and totaling them by hand?
Answered by Stephen La Rocque.
Three digit numbers 2007-04-19
From katelyn:
How many 3 digit numbers can be created if each number is a multiple of 10?
Answered by Penny Nom.
A four digit number 2007-03-28
From Paulo:
Hi , if i have to discover a keypad number of four digit , Which the closest combination of getting right?? i have this tips ---> i know the second and thirth number is odd . dont have the number 7 in any digit , Doesnt begin with 8 or 4 ... and dont have the 2 as a last number . Thanks !!
Answered by Stephen La Rocque.
Seven digit account numbers 2007-03-09
From Miranda:
Account numbers for the Central Oil Company consist of seven digits. If the first digit cannot be 0, how many account numbers are possible? Thank you so much!!!
Answered by Penny Nom.
The tens digit of a really large number 2007-03-05
From Sai:
How can i find the tens digit of a really large number? i was gven 63^15 + 15^63 in a competitive exam.
Answered by Penny Nom.
Four digit numbers 2007-02-26
From Anton:
Hello! I would like to ask you how many combinations are possible using 4 digit number. # # # # (1...9).There is no zero,numbers don't repeat,second and forth are odd.Thanks
Answered by Penny Nom.
A two-digit number is five times its units digit. 2007-02-21
From Pamela:
A two-digit number is five times its units digit. If the digits are reversed, the resulting number is 27 more than the original number. Find the original number.
Answered by Gabriel Potter and Penny Nom.
*** x ** = **** 2007-02-16
From Dani:
Use the numbers 1-9 only once to make the following: A three digit number times a two digit number that gives a four digit number. That is *** x ** = **** (the numbers 1-9 can only be used once for each star). I came up with the answer 138 x 42 = 5796 but I want to know whether this is the only solution and if not, is there a formula to come up with the answer. Thanks! I appreciate your help!
Answered by Chris Fisher and Claude Tardif.
Six digit numbers 2007-02-09
From marisa:
how many six digit numbers can you write using the digits 0 and 1 as many times as possible?
Answered by Stephen La Rocque.
The units digit of 9^2006 + 3^2006 2007-01-30
From Ryan:
What is the units digit of the sum of 9^2006 and 3^2006
Answered by Penny Nom.
The sum of the digits of a two-digit number is 13. 2007-01-27
From Liz:
The sum of the digits of a two-digit number is 13. If the digits are reversed, the new number is 9 more than the original number. Find the original number.
Answered by Penny Nom.
The units digit 2007-01-09
From Tyrone:
This may be a dumb question, but what is the unit digit of two digits, eg: 62 or 13 or 45.
Answered by Steve La Rocque and Diane Hanson.
2 digit combinations 2006-12-04
From Gary:
please figure out for me what are the 2 digit combinations of numbers using numbers 0 thru 9
Answered by Penny Nom.
Four two-digit numbers 2006-12-02
From Mary:
I have four two-digit numbers written on my paper. The sum of these 4 numbers is less than 100.

True or False - each number is less than 25

If all the numbers on my paper are different, what is the largest (two-digit) number I could possibly have written.

Answered by Stephen La Rocque.
My greatest digit is 9, ... 2006-11-17
From Tiffany:
My greatest digit is a 9, but less than 900. I'm one more than a multiple of 10 and the sum of my digits is 12. Who am I?
Answered by Penny Nom.
How can half of 12 be 7? 2006-11-16
From Liz:
How can half of 12 be 7?
Answered by Steve La Rocque, Chris Fisher and Penny Nom.
What is the highest number possible with 3 digits? 2006-11-16
From Liz:
What is the highest number possible with 3 digits? The teacher said the answer is not 999 and that the question did not say "3-digit number." My answer then is 9 to the 99th power (written mathematically of course) as this uses "3 digits" and is obviously a huge number. Is this correct?
Answered by Stephen La Rocque.
The units digit of 1^5 + 2^5 + ... + 2006^5 2006-11-14
From Lana:
Compute the unit's digit of :
1 to the power of 5 + 2 to the power of 5 + 3 to the power of 5 + 4 to the power of 5 + 5 to the power of 5 + 6 to the power of 5 + ... + 2006 to the power of 5 .

Answered by Stephen La Rocque and Penny Nom.
Four digit combinations 2006-10-26
From Sasha:
CAN YOU LIST ALL OF THE POSSIBLE 4 DIGIT COMBINATION'S, THAT DO NOT START WITH 0?
Answered by Stephen La Rocque.
Write the digits 1 to 9 on index cards, ... 2006-10-19
From Kim:
Write the digits 1 to 9 on index cards, arrange the cards to form three 3-digit numbers (using each card only ONCE). The third number is the sum of the first two numbers ** how many different ways can you do this?? **
Answered by Penny Nom.
The units digit of 12^40 2006-10-08
From Lana:
FIND THE UNITS DIGIT OF 12 TO THE POWER OF 40.
Answered by Penny Nom.
What number could it be? 2006-09-27
From Jonathan:
What number could it be?

It is between 12000 and 13000
Its hundreds, ten and ones digits are all odd
the sum of all its digits is 12.

Answered by Steve La Rocque and Claude Tardif.
A three-digit number multiplied by 7, then 11, then 13 2006-09-17
From Sherrie:
why is it true that a three-digit number multiplied by 7, then 11, then 13 will result in the three digits repeated twice?
Answered by Stephen La Rocque.
How many different three-digit numbers can you make using ... 2006-09-12
From Beth:
How many different three-digit numbers can you make using the numbers 2, 5, 7, 8 using the digits any number of times?
Answered by Stephen La Rocque and Penny Nom.
Two characters 2006-09-12
From Robert:
I am looking to find out how many possible unique combinations I can have if at any time i can use only two characters of numbers or the alphabet...For ex., i can have 1-99 or i can have a1, a2, z1, z2 ... or i can have aa, ab, ac... i came up with possible combinations of 1295 or so... can you help?
Answered by Penny.
The last two digits 2006-07-22
From Sam:
You have answered this question already but you only answered to one digit.

What are the last TWO digits of:
3 to the power of 1994
7 to the power of 1994
3 to the power of 1994 + 7 to the power of 1994
7 to the power of 1994 - 3 to the power of 1994


Answered by Paul Betts and Penny Nom.
The last digit of a six-digit number is 2. 2006-07-09
From GG:
The last digit of a six-digit number is 2. If the 2 is moved to the start of the number, the new six-digit number is only a third of the original number. Find the original number.
Answered by Paul Betts, Chris Fisher, Penny Nom.
How many digits are in the number 2^64? 2006-06-14
From Trang:
How many digits are in the number 264?
Answered by Stephen La Rocque.
We are 2 pairs of consecutive 2 digit numbers ... 2006-05-13
From A perent:
We are 2 pairs of consecutive 2 digit numbers that are factors of the number of feet in a mile. Who are we?
Answered by Claude Tardif.
10^100 in binary form 2006-05-10
From Headmaster:
How many digits has the number 10100 if we write it in binary form?
Answered by Chris Fisher, Paul Betts and Steve La Rocque.
8-digits numbers with their digits in decreasing order 2006-05-09
From Headmaster:
How many 8-digits number are there with their digits in decreasing order
Answered by Penny Nom.
A number theory problem 2006-05-05
From DeHayward:
Find the 6-digit number in which the first digit is one less than the second, the third is half of the second, the fourth is 3 times the third, and the last 2 digits are the sum of the fourth and fifth. The sum of all the digits is 24.
Answered by Paul Betts.
The sum of a three digit number and its three individual digits is 429 2006-04-08
From Megan:
Gill has recently moved to a new house, which has a three- digit number. the sum of this number and its three individual digits is 429. What is the product of the three digits which make up the house number?
Answered by Chris Fisher.
Four digit numbers 2006-03-25
From Kenvin:
i was wondering how many possibilities is there for a four digit number with the same first two numbers and the last two is not one of the first with numbers 1-9
Answered by Stephen La Rocque.
Five digit numbers 2006-03-25
From Tony:
Can someone tell me how many unique five digit numbers can be generated using 0-9?
Answered by Stephen La Rocque and Penny Nom.
The first six million digits of PI 2006-03-08
From Lori:
How many threes are there in the first six million digits of PI? Also how many nines?
Answered by Stephen La Rocque.
A nine digit number 2006-03-06
From Ryan:
What is the total number of possible combinations of a nine digit number (ie., social security number) including repeating numbers?
Answered by Stephen La Rocque and Penny Nom.
The units digit 2006-03-05
From Taran:
My teacher asked: What is the unit's digit in the product 5 X 10 X 15 X 20 X 25? What is a "unit's digit", what are they asking for?
Answered by Penny Nom.
Counting digits 2006-01-30
From Cynthia:
I would like to know the easiest way to calculate the total numbers of digits used by a printer to number the pages of a book from 1 to 250.
Answered by Penny Nom.
The number of combinations of the digits 0235588 2005-12-07
From Blake:
If you have the digits 0235588 how many different combinations can you possibly form with these seven digits?
Answered by Penny.
Fill in the blanks 2005-12-05
From Bonnie:
Distribute the numbers 1 through 9 on the lines below so that two equations are true.

_ _ x _ = _ _

_ x _ = _ _

Use each digit only once-

Answered by Penny Nom.
Add one 1 at the beginning and at the end of a number 2005-11-13
From Samuel:
If we add one 1 at the beginning and at the end of a number, this number is increased by 14789. What is the sum of the digits of the number?
Answered by Penny Nom.
5 digit numbers that include 5 and exclude 8 2005-11-04
From Paul:
figure out how many 5 digit numbers are there that include the digit 5 and exclude the digit 8. show me how to do get to the answer. (23816)
Answered by Paul Betts.
Four digit numbers 2005-10-09
From David:
I had a discussion with my father about how many four digit numbers you can make with 0-9. He was saying that there is 12,000 and that seems quite high for me. But can you tell me how many there are, and what exactly are they?
Answered by Penny Nom.
Three digit numbers 2005-10-04
From Jordan:
i need to know how many 3 digit numbers there are
Answered by Penny Nom.
What is the unit's digit? 2005-10-04
From Alex:

Question: What is the unit's digit of the following problem?

3155 + 7412 (3 to the 155th power + 7 to the 412th power.)


Answered by Penny Nom.
What is my number? 2005-09-16
From Bob:
I have 6 digits. 100,000th digit is one less than my ones digit, eight greater than my 1,000's digit, twice my tens digit and four times my 100s digit. My 10,000s digit is 0 What is my number?
Answered by Penny Nom.
What is the ones digit of 3 to the 79 power? 2005-09-14
From Candice:
What is the ones digit of 3 to the 79 power?
Answered by Penny Nom.
Whats the value of the digit 7 in 756,809? 2005-09-14
From Anastasia:
Whats the value of the digit 7 in 756,809?
Answered by Penny Nom.
n^2+n-1 has no divisors ending with 3 or 7 2005-09-08
From Arne:
at least it seems like for any integers n and k,
10k+3 and 10k+7 do not divide n²+n-1
I tested this for every n from 0 to 3200 (which means same for the numbers from -3201 to -1)
could this be true, or is it just coincidence, or am I just totally wrong?

Answered by Richard McIntosh.
The number of four digit combinations 2005-08-09
From Kevin:
My 12 year old has asked me how to figure out the number of four digit combinations possible using 0 thru 9 without repeating a number?
Answered by Penny.
A two digit number 2005-08-09
From Grace:
I am a 2 digit number. Both of my digits are even. My tens digit is 8 more than my ones digit. What number am I?
Answered by Penny Nom.
The sum of the digits of 2^100 2005-06-11
From Richard:
The sum of the digits was calculated for the number 2100, then the sum of the digits was calculated for the resulting number and so on, until a single digit is left.
Answered by Penny Nom.
How many digits? 2005-06-07
From Floren:
The numbers 21989 and 51989 are written one after another. How many digits in all are there?
Answered by Claude Tardif.
The units digit 2005-05-18
From Gerald:
Juan wrote the first 12 powers of 2. He noticed a pattern in the digits in the units places of the results. He said he could use this pattern to predict the digits for 2 to the power of 100.
Answered by Penny Nom.
A six digit answer 2005-05-18
From Angela:
I have a 6 digit answer that is comprised of only 4 symbols: a square, a circle, a triangle, and an X. How many possible solutions are there and how is the best way to find out what ALL the solutions are?
Answered by Penny Nom.
Some four digit numbers 2005-04-16
From Lori:
can u give me every possible combination of four numbers starting with the number three
Answered by Penny Nom.
The sum of the digits 2005-03-16
From kelsey:
What is the sum of the digits in the decimal form of 21999 * 52002?
Answered by Claude Tardif.
How many three digit numbers can I make from the four cards 2005-03-12
From Sue:
I have four playing cards 2,3,4,5 of hearts. How many three digit numbers can I make from the four cards.
Answered by Penny Nom.
Six digit numbers with at least one 7 2004-12-27
From Behzad:
How many six-digit numbers contain at least one 7 in their decimal expansion?
Answered by Penny Nom.
Strings of 4 digits from 1,2,...,7 2004-12-09
From Tom:
How many different combinations can be made of the numbers 1-7 in 4 string combinations in any order? EX:7-2-3-5, 3-5-1-7, etc...
And if you were to include the same 2 numbers in every combination, how many would that make? EX: Using 1 & 2: 1-2-7-4, 5-1-4-2, 2-7-5-1, etc...

Answered by Penny Nom.
The last digit of a large exponent 2004-10-20
From Landon:
How can one determine the last digit of a large exponent by hand. I have seen several examples of how to do this by breaking it up into smaller exponents, but is there a formula or some common things to look for?
Answered by Penny Nom.
A five digit number 2004-10-06
From A parent:
What is the 5 digit number in which the first 2 digits are the square of the 3rd digit and the last 2 digits are the square of the digit that is one less than the third digit? The sum of all the digits is 22.
Answered by Penny Nom.
A palindrome question 2004-09-28
From Lilly:
12, 21, 13, and 31 are the only double-digit numbers whose squares are the palindromes of the squares of the palindromes of double-digit numbers. I was wondering why it works for these numbers, and if only these numbers work this way.
Answered by Chris Fisher and Penny Nom.
The last digit of 2^28 2004-09-25
From A student:
I am currently enrolled in a math reasoning class and a math question I have to answer is determine the units digit in 3 28power. When I set up a table and keep cubing the numbers, I find a pattern with the last digits of the numbers that follow 1,3,9,7. My calculator gets to about the 19th power, and then I get an error. If I continued the pattern, would the units digit then be the last digit of 3 28th power, which would be a 7? Please let me know if I am solving this correctly and what a unit's digit actually is.
Answered by Penny Nom.
Four and five digit numbers 2004-09-21
From Josy:
The question I have now in front of me is....Is a 4-digit number always less than a 5-digit number? Hi Josy, The digits in order are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. Thus the largest four digit number is 9999. The smallet 5 digit number is 10000. Penny Go to Math Central
Answered by Penny Nom.
Some numbers less than 100 2004-09-17
From Paul:
for how many numbers less than 100 is the digit in the ones place half the digit in the tens place?
Answered by Penny Nom.
The bar over repeating digits. 2004-09-07
From Debbie:
I would like to know the name given to the bar that is written over the repeating digits of a decimal.
Answered by Penny Nom.
Four digits 2004-07-10
From Rob:
I am always interested to know how the for digit works. I mean, you have correctly put it that the total numbers obtain from 0000 thru 9999 are 10,000. My question is, is there any simple formula to turn this simple 4 figures of say: 1234.
Answered by Penny Nom.
Jack's social security number 2004-06-08
From A student:
Jack's social security number contains each of the nonzero digits exactly once. By examining the digits from left to right, he also found that 1 divides the first digit evenly, 2 divides the sum of the first two digirs evenly, 3 divides the sum of the first three digits evenly, and so on, until 9 divides the sum of all the digits evenly. What is Jack's social security number?
Answered by Penny Nom.
A 3 digit number divisible by 7 2004-05-03
From A student:
We need to arrange 1,3 and 6 to form a 3 digit number that is divisible by 7.
Answered by Penny Nom.
Setting up an equation 2004-04-30
From Matt:
I am trying to determine the dimensions of a 22 megapixel digital camera chip that has a 3:2 ratio. We know then, that: 3x = 2y (or 1.5x = y)

and that

xy = 22

Beyond this, I don't know how to hook those 2 seemingly unrelated facts together.

Answered by Penny Nom.
The units digit of 4^478 2004-03-06
From Elizabeth:
What is the units digit of 4478?
Answered by Penny Nom.
Digits in the decimal expansion 2004-02-11
From Leslie:
In the decimal expansion of 1/17 what digit is in the 1997th place?
Answered by Penny Nom.
Three digit combinations 2004-01-27
From Kevin:
how many 3 digit combinations can be made with 0-9. i have been told only 1,000. when i asked jeeves the response was 750 without using any digit twice. i have entered a raffle and received a ticket with 4 sets of 3 digit numbers.
Answered by Penny Nom.
Four digit combinations 2003-12-31
From A student:
i need all 4 digit combinations using 0-9 please
Answered by Penny Nom.
Four digit numbers 2003-11-20
From Rob:
Hello, I sure hope you can answer this question. I got into a discussion at work about how many possible combinations there are for a four digit number using the numbers 0 through 9. This was in reference to a discussion about the lottery. I said there was only 10,000 possible combinations. My friend said that there was many times more, but he could not remember how to figure it out. The answer and the formula would be greatly appreciated.
Answered by Penny Nom.
The digits in 349 2003-09-12
From Franik:
in the number 349, which number has the least value, and why?
Answered by Penny Nom.
7,473,000,000 divided by 52000 2003-09-06
From A student:
I am having trouble with a question. 7,473,000,000 divided by 52000. Our calculater gets 147311.5385. I come up with 143711.53846, and then the number starts to repeat itself
Answered by Penny Nom.
Four digit combinations 2003-09-04
From Emma:
I seriously need to find out all the four digit combinations from 0 to 9!!! My name Is Emma Dibitt and I'm going into 8th grade and I'm a student!!!
Answered by Penny Nom.
The units digit of 57 to the 28th power 2003-09-01
From Maria:

If 57 is raised to the 28th power, what must be the units digit in the result?

If you raise 7 to the 500th power, what is the numeral that will appear in the units digit position?


Answered by Penny Nom.
39 consecutive natural numbers 2003-08-19
From A student:
Prove that among any 39 consecutive natural numbers it is always possible to find one whose sum of digits is divisible by 11.
Answered by Penny Nom.
The number of three digit combinations 2003-08-16
From Fred:
There are four close friends having a heated discussion concerning the the number of three digit combinations using the numbers 0 through 9. The discussionÝinvolves the daily lottery.Ý Any assistance you can lend would be greatly appreciated.
Answered by Penny Nom.
Inserting a comma ever three digits 2003-07-25
From Linda:
when writing a large number, why do we insert a comma every three numbers instead of every two or four numbers?
Answered by Penny Nom.
nine digit numbers 2003-07-23
From John:
With a nine digit number, with each of the nine digits having a possibility of 10 different numbers then what is the total number of possible mathematical variations in the nine digit number. i.e. Social Security numbers have nine digits and if each of the nine digits have a possibility of being any one of ten numbers, i.e. 0,1,2,3,4,5,6,7,8,9. Then what is the formula to calculate the maximum possible number of variations in this nine digit number and what is the mathematical maximum possible number of variations of this nine digit number?
Answered by Penny Nom.
Four digit palindromes 2003-05-05
From Heather:
How many palindromes were in between the numbers 1000 and 9999?
Answered by Penny Nom.
Three digit number 2003-03-10
From Grace:
What three digit positive integer is exactly 32 times the sum of its digits?
Answered by Claude Tardif.
Combinations of 1,2,3,4,5 and 6 2003-02-01
From Kyle:
Today I was aked a question by my geometry teacher. It was, what is the sum of all the possible combinations of the numbers 1, 2, 3, 4, 5, and 6. He said all the possible combinations were 720. I would like to know how u could do this, and what the answer is.
Answered by Penny Nom.
6 digit numbers from 0,0,2,2,4,4 2003-01-23
From Amanda:
How many 6 digit numbers can you make from the numbers 0,0,2,2,4,4, giving that 0 cannot come first. The number has to contain 2 twos, 2 fours, and 2 zeros.
Answered by Penny Nom and Claude Tardif.
The units digit of 2 to the power of 31921 2002-12-18
From A student:
If 2 to the power of 31921 is multiplied out, what will be the units digit?
Answered by Penny Nom.
ALL of the possible 3 digit combinations of 0 - 9 2002-12-09
From Melissa:
I need to find out ALL of the possible 3 digit combinations of 0 - 9. Eg: 000,001,002,003. This is going to take me VERY LONG time. Any suggestions.
Answered by Penny Nom.
65,125 2002-12-04
From Brittany:
I am a three-digit number.When you reverse my digits,a larger number is formed.the product of me and the new number is 65,125.What number am I.
Answered by Chris Fisher and Claude Tardif.
4 x abcd = dcba 2002-11-20
From A student:
Say you have a four digit number (e.g. abcd) and you multiply the number by 4. The answer you get will be the reverse order of the number you started with (dcba). What is the number? The four digits (a,b,c,d) cannot be the same number or cannot be repeated.
Answered by Penny Nom and Claude Tardif.
Rounding 27.27 2002-11-03
From A parent:
If you have a problem 27.27 and you need to round to the first 7 the answer would be 27

Would 27.0 be acceptable as well or is it completely wrong.


Answered by Penny Nom.
What are the digits? 2002-10-24
From Ebenezer:
There are three digits. The middle digit is zero and the sum of the first and last digits are is 13. When the number is reversed it is increased by 297. What are the digits?
Answered by Penny Nom.
Use each digit 1-9 only one time each,... 2002-10-19
From Megan:
Use each digit 1-9 only one time each, divide the numbers into 3 groups, make one 2 digit number, one 3 digit number, and one 4 digit number. There are 6 combinations of these numbers in which you can multiply the 2 digit and 3 digit number together to get the 4 digit number (using each digit 1-9 one time each). What are they!!!!!!!!!????????????
Answered by Claude Tardif.
I am a 3 digit number. 2002-09-06
From Jasmine:
I am a 3 digit number. My last digit is 3 times my first digit. My firat digit is twice my middle digit. What numbers am I? There are at least 2 correct answers?
Answered by Paul Betts.
Counting 2002-06-21
From Rachel:
How many different numbers of 2 different digits each can be formed using the digits (1,3,5,7,9)?

How many triangles are formed by the vertical of a regular hexagon?

Answered by Penny Nom.
Numbering pages 2001-11-15
From Lucy:
A printer uses 1008 digits to number the pages of a book. How many pages are there in the book?
Answered by Penny Nom.
Squares of one digit numbers 2001-10-15
From Needa:
What two two-digit numbers are each equal to their right-most digit squared?
Answered by Penny Nom.
The 100 chart 2001-09-28
From Nich:
Am I suppose to use the 100 chart for these questions.

Question One:
I am a 2 digit number my tens digit is 2 more than my one digit my 1 digit is between 4 & 6. What # am I ?

Question Two:
I am a 2 digit # I am greater than 40 but less than 60 my tens and ones digits are the same I am a odd number what am I ?


Answered by Penny Nom.
4 digit combinations 2001-09-22
From Laura:
I need all of the 4 digit combinations using the numbers 0-9.
Answered by Harley Weston.
I have 6 digits. 2001-09-06
From Kristan:
I have 6 digits. My hundred thousands is 1 less than my 1 digit, 8 greater than my thousands digit, twice my tens digit, and 4 times my hundreds digit. My ten thousands digit is 0. What # am I?
Answered by Penny Nom.
Generating uniquie 2 digit numbers 2001-07-16
From Anthony:
What methodology can I use to generate uniquie 2 digit numbers from unique 7 digit numbers. Of'course the total number of 7-digit numbers is not greater than 99.
Answered by Penny Nom.
Four digit numbers from 1,2,3,4,5,6,7,8 2001-05-31
From Katie:
Okay.......here's my question...how many different ways can you form a four digit number out of these digits..1,2,3,4,5,6,7,8? This is how my teacher said to do this.... 8*8, 7*7,6*6,5*5,4*4,3*3,2*2,1*1. then she said to add up the products and to multiply by 7. is this correct, and if not how can you figure this out.
Answered by Penny Nom and Claude Tardif.
How many 6 digit numeral combinations 2001-04-26
From Bryan:
How many 6 digit numeral combinations are there If you can only use 6 digits (1, 2, 3, 4, 5, 6) and no number can be used twice in the Numeral!
Answered by Claude Tardif.
The number of occurrences of 0 is __, of 1 is __, of... 2001-04-17
From Martyanne:
"In this sentence the number of occurrences of 0 is __, of 1 is __, of 2 is __, of 3 is __, of 4 is __, of 5 is __, of 6 is __, if 7 is __, of 8 is __, of 9 is __."

Each blank is to be filled with a numeral of one or more digits, written in decimal notation.

Answered by Claude Tardif.
The repetend in repeating decimals 2001-03-21
From Sharon:
What is the name for the bar over the repetend in repeating decimals? Also, what is the name of the long division "house"?
Answered by Penny Nom.
Probability and a three digit number 2001-03-15
From Glenn:
A THREE DIGIT NUMBER IS SELECTED AT RANDOM. WHAT IS THE PROBABILITY THAT NON OF THE THREE DIGITS ARE PRIME.
Answered by Harley Weston.
Multiplying one and two digit numbers 2001-02-11
From Marty:
When multiplying do you put the number you are multiplying by on the top or the bottom. Example if you are multiplying by 6's would you write the problem 6
x 2
or 2
x 6
Maybe it just doesn't matter. But when you get to double digits, the double digit always goes on the top?

Answered by Penny Nom.
The sum of all ten-digit numbers. 2001-01-10
From John:
Compute the sum of all ten-digit numbers. Can you determine the sum of all n -digit numbers?
Answered by Sukanta Pati.
Divisibility by 16 2000-12-12
From Shiling:
A number can be divided by 16 if and only if its 1st four digits can be divided by 16. How can you prove that?
Answered by Penny Nom.
Five digit palindromes 2000-11-12
From Jacky:
Positive integers such as 1287821 and 4554, in which the number is unchanged when the digits are reversed, are called palindromes. The number of five-digit integers larger than or equal to 10,000 which are not palindromes is... a. 10 000 b. 81 000 c. 89100 d. 90 000 e. 99 100
Answered by Penny Mom.
4-digit numbers using 7, 8, 9 and 0 2000-09-13
From Ryan:
Could you please help me with the following problem, How many different 4-digit numbers are there that use each of the digits 7,8,9,and 0? Please list them.
Answered by Penny Nom.
The units digit of 3 to the 58th power 2000-05-10
From Kylie Mcalpine:
the questions we have been asked are what is the units digit of the following:

a) 358
b) 2358
c) 1731

and the harder question of:

what is the units digit of the following sum: 13841 + 17508 + 24617 = ???????


Answered by Paul Betts and Penny Nom.
Six digit numbers using 1,2,5,6,7, and 9 2000-03-20
From Rachel:
How many different six-digit numbers can you make using the digits 1,2,5,6,7, and 9? How many of these six digit numbers are divisible by six?
Answered by Claude Tardif and Denis Hanson.
A three digit number 2000-01-13
From Manali Shah:
My son is in 5th grade, he has a math problem. There is three digit number, which is greater than 500, can be divided by 7,9 and 11, but cannot be divided by 2,4,6, and 5.
Answered by Harley Weston.
Bases other than 10 1999-12-06
From Garret Magin:
We are doing a lesson on numbers of other bases than 10. We are working with binary, octal, and Hexadecimal. I was wondering what is used to represent number of different bases other then 16? Does it just continue on with the alphabet and if so what happens when you get to Z. It would be a help if you could answer this because it is really bugging me. And none of the math teachers at my school could let me know.
Answered by Claude Tardif and Patrick Maidorn.
0! + 1! + 2! + 3! + ... + 2000! 1999-10-21
From Melissa:
My name is melissa. I am a 9th grade student I am having trouble finding out how to do this: What is the tens digit of 0! + 1! + 2! + 3! + ... + 2000! I know how to find these, but my calculator cant go any higher than 69! Is there any way i can do this problem?
Answered by Penny Nom.
Numbers with the digit 2 in 1...1000 1999-09-20
From Jessica:
Is there a trick to finding out how many numbers containing the digit two is there from 1 to 1000?
Answered by Walter Whiteley.
A Puzzle 1998-10-27
From Bruce Bragnu:
We are trying to solve what SHOULD BE a simple 7th grade problem and have run into a wall.
It is:
ABCD
ABCD
ABCD
ABCD
-------
EBEA

It is an addition problem. Each particular letter represents the same digit. We are looking for what number "B" represents. We have tried a multitude of solutions and have come up empty.
Answered by Penny Nom.

A Six Digit Number 1998-10-27
From Craig Bedard:
If a certain six-digit number is split into two parts, one constituting the first three digits and the other the last three digits, and the two parts are added and the resultiong sum squared, it is found that the product is the original six digit number. What is the original six-digit number?

At first it seemed liked an impossible question, until it hit me...how long will it take you?
Answered by Jason Stein and Dan Usselman.

Social Security Numbers 1998-07-07
From Valerie Lucas:
How many social security numbers are possible?

the answer is 10^9

why isn't the answer 9^9?
Answered by Harley Weston.

The two-digit numbers from 10-99 1998-01-21
From Alexis Riddle:
My name is Alexis. I'm a student in 8th grade and I'm taking Algebra I Honors. My question is: In a string of numbers, two adjacent digits are considered as a two-digit number. For instance, the string 11012 contains the numbers 10, 11, and 12. What is the number of digits in the smallest string that contains all of the two-digit numbers from 10-99? Please help and thank you for any assistance you can give me.
Answered by Penny Nom.
Driving me CRAZY. 1997-11-17
From Billy Tran:
Write a two digit number (both digits different and neither equal to zero) and then express the same number but now composed of the same two digits in reverse order with some mathematical symbol (+, -, *, /, roots, !, or exponents). for example: 25 = 5^2. Now give me another.

Hope you get this, cause its driving me CRAZY
Answered by Penny Nom.

How many digits are there in 2^2520? 1996-10-07
From Rita Leung:
A)The number 64 is a sq., a cube, and a sixth power because 64=8*8, 4*4*4, 2*2*2*2*2*2. Find the smallest integer greater than 1 that is a sq., a cube, a 4th, 5th, 6th, 7th, 8th, 9th and 10th power. I have found that the answer is 2 to the power 2520th.
B) How many digits are in the correct answer to part A? The answer is uncertain. It is either 758 or 759. Can you give me any ideas?

Answered by Penny Nom.
Repeating decimals 1996-09-09
From Alice:
What is the line called that is placed over the decimal to show that it is infinitely repeating?
Answered by The Centralizer.
 
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