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prime

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27000001 2017-10-09
From Tulashiram:
If a× b =27000001, then what is the value of a & b ?
Answered by Penny Nom.
Factors 2017-08-16
From Gemma:
Why do 315 and 525 have the same number of factors?
Answered by Penny Nom.
The product of a 2-digit number and a 3-digit number 2015-02-06
From Nathaniel:
The product of a 2-digit number and a 3-digit number is about 50 000 what are the products
Answered by Penny Nom.
Mutually prime composite numbers 2015-01-09
From nivedita:
Two composite number that is mutually prime?
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.
Prime factorization in exponent form 2014-10-31
From Emma:
I need to find out how to make a prime factorization of 120 in exponential form.
Answered by Penny Nom.
Sieve of Eratosthenes 2014-10-03
From Hope:
using Sieve of Eratosthenes to determine for in instance prime numbers between 1 to 200, to what nth number should i stop?, 4th, which is 11 or what?
Answered by Robert Dawson.
Prime factorization 2014-02-06
From Kadeejah:
Write the prime factorization of 37 in exponential form
Answered by Penny Nom.
GCD 2013-05-20
From Julia:
Prove that if a and b are coprime integers, the greatest common divisor of a + b and a - b is either 1 or 2.
Answered by Penny Nom.
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.
What is the prime factor form of 7/5? 2012-04-17
From David:
What is the prime factor form of 7/5
Answered by Robert Dawson.
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.
The LCM of 6,15 and x is 90 2011-10-30
From Richie:
Hi there,
There are 2 parts to the question.
#1. Factorise 90. This is easy, 90=2x3x3x5

#2
LCM of 6,15 and x is 90. What are possible values of x if x is odd?

From #1, since 90=6x15, how can this be used to work out possible values of x?

Thanks in advance, Richie

Answered by Penny Nom.
One factor array 2011-09-16
From Hana:
hi my brother a 5th grade have a question. this is what it say "i have only one factor array, and i am between two numbers 12 and 16. what number am i?"
Answered by Penny Nom.
What is the largest prime number? 2010-11-20
From vadali:
what is the largest prime number?
Answered by Penny Nom.
Powers 2010-10-20
From dylan:
how do you write 20736 in exponential form .same for 1728 and 50625.

is there a formula to figure out how to express large know numbers in exponential form.

Answered by Penny Nom.
Adding five positive integers that have a product of 48 2010-04-27
From Lorraine:
What is the smallest possible sum that can be obtained by adding five positive integers that have a product of 48.
Answered by Chris Fisher.
The cardinality of the prime numbers 2009-11-07
From Justin:
Hello there, I was just wondering since the number of primes is infinite, are they equal to infinity or Aleph-null? Justin
Answered by Robert Dawson and Victoria West.
The cube of a number plus five times the number plus 1 2009-10-12
From JP:
Find a counterexample to the statement: The cube of a number added to the sum of five times the number and 1 is a prime number.The cube of a number added to the sum of five times the number and 1 is a prime number
Answered by Penny Nom.
What is my number? 2009-09-18
From Hanna:
What is my number?
My number is a perfect square.
The only number in its prime factorization is 2.
My number is a factor of 32.
The sum of its digits is odd.

Answered by Penny Nom.
Exponential form 2009-08-31
From cecil:
what is the exponent form 564000?
Answered by Stephen La Rocque and Harley Weston.
Primes 2009-06-25
From Chinonyerem:
If p = 2^k - 1 is prime, show that k is an odd integer, except when k = 2. [ Hint: 3/4^n - 1 for all n >= 1.]
Answered by Robert Dawson and Penny Nom.
GCD (a + b, a - b). 2009-04-01
From Tomas:
Let a and b integer and relatively prime. Prove that:
GCD (a + b , a - b) = 1 or 2

Answered by Stephen La Rocque.
The factors of an integer 2009-01-06
From Madison:
what are the factors of 878
Answered by Robert Dawson.
Do all square numbers have an odd number or factors? 2008-12-11
From Amy:
Do all square numbers have an odd number or factors?
Answered by Victoria West.
Some number theoretic speculations 2008-12-04
From Andrew:
Another way of looking at the 'alternating parity polynomial', again based on Fermat's Little Theorem, is to substitute (a - b) for x in x^(p-1) - 1 as this is always divisible by any prime p. So, if one removes the "- 1", there is always a remainder of (1/p)! (I took up your challenge!)
.
.
.

Andrew

Answered by Chris Fisher and Victoria West.
Primes and polynomials 2008-11-24
From Andrew:
How effective are the two
pairs of polynomials, taken together, at "excluding" any prime p.

1. (a^2 - a.b + b^2) and (a^2 + a.b + b^2) Where b > a > p and (a, b, p) = 1

2. (c^2 - c.a + a^2) and (c^2 - c.b + b^2) Where c > b > a > p and (a, b, c, p) = 1
Answered by Victoria West.

A question about primes and polynomials 2008-11-16
From Andrew:
Is it possible for (a^2 - a.b + b^2) to be divisible by a prime p where b > a > p and a, b, and p are relatively prime? I let a = n.p + x and b = m.p + y (where both x and y are < p) and after dividing throughout by p one gets to decide whether (x^2 - x.y + y^2) ==0 mod(p) ?! It seems unlikely unless p = (x^2 - x.y + y^2)? (Note:- All letters represent positive integers.)
Answered by Chris Fisher and Victoria West.
The prime factorization of one billion 2008-11-02
From Alta:
The prime factorization of 1000 is 2 cubed times 5 cubed. How do you write the prime factorization of one billion using exponents?
Answered by Penny Nom.
Prime factorization 2008-10-19
From nick:
while im doing prime factorization for one number and it cant be divided 2,3 or five so what next?
Answered by Penny Nom.
Product of Two-Digit Numbers 2008-07-31
From pete:
The number 4641 can be expressed as the product of two two-digit whole numbers. What is the sum of these two numbers?
Answered by Janice Cotcher.
Neither prime nor composite 2008-07-08
From saloni:
Give the counting number which is neither prime nor composite ?
Answered by Penny Nom.
The square root of (18*n*34) 2008-07-01
From Peter:
What is the least possible positive integer-value of n such that square root(18*n*34) is an integer?
Answered by Penny Nom.
The smallest number divisible by 1 to 9 2008-06-26
From Peggy:
What is the smallest number divisible by each of the first nine counting numbers?
Answered by Penny Nom.
Prime factors 2008-05-21
From john:
the first 5 prime numbers are 2,3,5,7,11. which is the smallest number that has these prime factors.
Answered by Stephen La Rocque.
Why is the number 1 neither prime nor composite? 2008-02-07
From ronni:
why is the number 1 neither prime nor composite?
Answered by Harley Weston.
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.
(1x2x3x...n)+1 2008-01-29
From Sayuri:
what is the smallest natural number n, greater than 1, for which (1x2x3x...n)+1 is not a prime?
Answered by Penny Nom.
Prime factorization 2007-11-11
From jeff:
find the prime factorization and use exponential notation for 432
Answered by Penny Nom.
Why is the number 1 neither prime nor composite? 2007-11-08
From amarilis:
why is the number 1 neither prime nor composite?
Answered by Penny Nom.
I am a prime number 2007-10-31
From sherry:
I am a prime number. I can not be shared fairly except by one group. My array can only be one row. array can only be one row. Can you please explain this out to me so I can help my child with it. Thanks
Answered by Penny Nom.
An array for 31 2007-10-31
From sherry:
How do you make an array with the number 31
Answered by Penny Nom.
13 year and 17 year locusts 2007-10-12
From stefan:
how many years pass between the years when both 13 year and 17 year locusts are out at the same time?
Answered by Penny Nom.
Cubes 2007-09-21
From Yvonne:
The numbers 756 and 72, expressed as products of prime factors, are 756 = 2² x 3³ x 7 and 72 = 2³ x 3²

Use these result to find,

the smallest integer, x, such that 756x is a perfect cube.

Answered by Penny Nom.
Prove that any two consecutive integers are relativley prime. 2007-09-18
From Michael:
Im not very good at proofs and I was wandering if you would be able to help me with the following question: Prove that any two consecutive integers is relativley prime. Thanks a million.
Answered by Penny Nom.
How far from n do you need to go to have found at least one prime? 2007-09-16
From Mike:
Hi, I was wondering if there was some kind of guaranteed interval that ensures that if you start at some number n, you will always have passed a prime number p. I remember having once read something that there is always at least one prime between n and 2n, but I cannot for the life of me remember where I read that, or what that kind of rule would be called so I can look it up online... thank you for your help, Mike
Answered by Penny Nom and Victoria West.
Prime factors in exponential form 2007-09-06
From Michelle:
how would you write this: factor 48 as a product of primes written in exponential form
Answered by Stephen La Rocque.
How many stairs in the flight are stepped on exactly once? 2007-09-03
From Bill:
Four friends are racing together down a long flight of stairs. A goes 2 steps at a time, B 3 at a time, C 4 at atime and D 5 and at a time. The only steps on which all four tread are the top one and the bottom one. How many stairs in the flight are stepped on exactly once.
Answered by Harley Weston.
Prime numbers and square numbers 2007-05-22
From Naseer:
I read somewhere that prime number can be a factor of square only if it occurs at least twice in its square please explian this with examples.
Answered by Penny Nom.
If the product of A,B,C is 15834, what is A+B+C? 2007-03-10
From rachel:
if the product of A,B,C is 15834, what is A+B+C?
Answered by Penny Nom.
Is c relatively prime to (n.p)? 2007-03-02
From Andrew:
Please could you help me with a small mathematics problem?! I've put = the problem into three parts but it isn't really three problems; just = one! Given:- {[(n.p)^p] / [c + (n.p)]} =3D "an integer" (where c > = (n.p); c and n are integers, n is even and p is an odd prime number) Can one prove that c cannot be relatively prime to (n.p)? { i.e. c = must have the factor (n.p) ?} If so, is the converse also true? {i.e. If c is relatively prime to = (n.p), then [c + (n.p)] cannot be a factor of (n.p)^p ?} Lastly but similarly, if c is relatively prime to a and c > a > = (n.p) ; (c - a) > (n.p) **; and c is not relatively prime to (n.p) = would it be true that (c - a) cannot be a factor (n.p)^p ? I hope my question makes sense?
Answered by Penny Nom.
Three distinct prime factors 2007-02-15
From nick:
what is the smallest natural number that has three distinct prime factors in its factorization
Answered by Stephen La Rocque.
Why zero is neither prime nor composite? 2007-01-17
From Brenda:
Why zero is neither prime nor composite?
Answered by Penny Nom.
Prime numbers 2007-01-16
From A student:
are the product of two prime numbers always prime?
Answered by Penny Nom.
Show that 3k+2 and 5k+3 are relatively prime 2007-01-15
From Andrea:
show that if k is a positive integer, then 3k+2 and 5k+3 are relatively prime
Answered by Penny Nom.
The sum of prime numbers 2006-11-28
From Rambabu:
I would like to know the sum of prime numbers below some X say 10000. Provide me with easy way to get this done
Answered by Penny Nom.
The greatest common factor of two numbers 2006-07-16
From Fadwa:
What is the greatest common factor(GCF) of the following algebraic expressions? 1680 and 6048
Answered by Stephen La Rocque.
How many numbers are relatively prime with 250? 2006-04-19
From David:
How many positive integers less than or equal to 250 are relatively prime with 250?
Answered by Stephen La Rocque.
given that p is a prime and p|a^n, prove that p^n|a^n 2006-03-24
From Janna:
given that p is a prime and p|an, prove that pn|an
Answered by Stephen La Rocque.
The Least Common Multiple of two primes 2006-02-21
From Kristine:
Is the Least Common Multiple to two prime numbers always their product? Why or Why not?
Answered by Stephen La Rocque.
How many divisors does the number 138600 have? 2006-02-08
From Joe:
How many divisors does the number 138600 have?
Answered by Steve La Rocque and Penny Nom.
Write the array for 3 2006-01-29
From Jamie:
My son is a 5th grader and came home with a math question that I can't answer. The question stated - "Write the array for 3" I don't understand how this can be done with just one number.
Answered by Penny Nom.
GCF, LCM, primes and the ladder method 2006-01-07
From Linda:
How would I teach both finding the GCF and LCM with prime factors...I recall the ladder method vaguely.???
Answered by Penny Nom.
LCM 2005-12-12
From Alex:
what is the LCM of 210 and 54 and the LCM of 42 and 126
Answered by Penny Nom.
Divisibility by each of the first ten counting numbers 2005-10-17
From Simon:
determine smallest positive integer that is divisible by each of the first ten counting numbers
Answered by Penny Nom.
A two digit prime 2005-09-12
From A student:
The units digit of a two-digit prime number is not greater than the tens digit by 3.If the positions of the two digits are interchanged, then the new number formed is greater than the original number by more than 18. Find the value of the original prime number.
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.
Three prime numbers p,q and r, all greater than 3, form an arithmetic progression: 2005-07-18
From Ladis:
Three prime numbers p,q and r, all greater than 3, form an arithmetic progression: p=p, q=p+d and r= p+2d. Prove that d is divisible by 6.
Answered by Chris Fisher.
p+1, p+2 y p+4 are prime 2005-06-18
From Vincent:
Find all the values of p (where p is a natural number), for which the numbers p+1, p+2 y p+4 are prime.
Answered by Penny Nom.
Primes 2005-06-04
From Fede:
Prove that there is not a number prime p, for which the numbers p+5 and p+10 are prime too.
Answered by Penny Nom.
The numbers p and 8p^2 +1 are prime. 2005-05-30
From Antonio:
The numbers p and 8p2 +1 are prime. Prove that the number 8p2+2p+1 is also a prime number.
Answered by Claude Tardif and Penny Nom.
Prime numbers 2005-04-11
From Jesule:
Given that p, p+10 and p+14 are prime numbers, find p.
Answered by Claude Tardif and Chris Fisher.
Numbers that John likes 2005-01-16
From Garrett:
John likes 400 but not 300; he likes 100 but not 99; he likes 3600 but not 3700. Which does he like?

900
1000
1100
1200

Answered by Penny Nom.
252 x ? is a cube 2004-12-22
From Andrea:
What is the smallest positive interger by which 252 can be multipled so the result is a perfect cubed?
Answered by Penny Nom.
The lcm of 5, 3, 4, 7 and 2 2004-11-05
From Christine:
what is the lcm of 5,3,4,7,2
Answered by Penny Nom.
an integer with three factors 2004-08-03
From A student:
What is the probability that a randomly chosen 3 digit number has exactly 3 factors
Answered by Penny Nom.
Divisors of 2n+1 and 3n+9 2004-06-02
From Chris:
Amy selected a positive integer N and wrote numbers 2xN+1 and 3xN+9 on a whiteboard. Boris looked at the two numbers on the whiteboard and wrote in his notebook a positive integer that divides each of them. Find all possible numbers that Boris could have written in his notebook.
Answered by Chris Fisher and Penny Nom.
(2^ 20,966,011) - 1 2003-12-12
From Reid:
Can someone please explain, answer and/or solve this: (2^ 20,966,011) - 1

I don't know what it means, my boss sent it out, I'm assuming it is to be solved but don't know what it is, any prompt help would be appreciated, very much so, in fact, thanks,...........


Answered by Penny Nom.
If 1 is neither prime nor composite... 2003-11-19
From Joshua:
if 1 is neither prime nor composite...what is it called?
Answered by Claude Tardif and Penny Nom.
If 1 is neither prime nor composite... 2003-11-19
From Joshua:
if 1 is neither prime nor composite...what is it called?
Answered by Claude Tardif and Penny Nom.
What is a number that has exactly 13 factors? 2003-11-09
From Mary:
What is a number that has exactly 13 factors?
Answered by Penny Nom.
Pairs of prime numbers 2003-10-13
From Nikolas:
Use pairs of prime numbers to find all the numbers less than 50 that have only two prime factors. Make an organized list.
Answered by Penny Nom.
Relatively prime 2003-09-27
From James:
what is the definition a relative prime numbers?
Answered by Penny Nom.
Primes 2003-09-23
From Julie:

#1. Suppose you are given a number (n) and told that 1 and the number (n) divide into (n). Does that mean (n) is prime?

#2. Suppose that p is a prime number greater than or equal to 3. Show that p+1 cannot be a prime number.


Answered by Penny Nom.
The Sieve of Eratosthenes 2003-09-18
From Lynn:
My daughter has been asked to find all the prime numbers by using the Sieve of Eratosthenes. I have no understanding what this means.
Answered by Penny Nom and Claude Tardif.
Making a square 2003-09-07
From A student:
if I am given any number (say 80 for example), how may I determine the smallest whole number integer which when multipled by it will yield a square number ? In other words if I express this as: 80Ý*ÝnÝ=ÝsquareÝnumber, what is the least value of n which will yield a square.
Answered by Penny Nom.
1575 2003-03-13
From Sharyn:
find 6 integers that when multiplied with each other equal +1575 and when the same integers are added together equal zero. there are more positives than negatives and one of the numbers is a double digit between 10 and 20
Answered by Penny Nom.
X times Y equals ten million 2003-02-26
From Baneen:
Would you be able to tell me which two numbers would compute ten million without any number having zeros in it?
Answered by Penny Nom.
Composites, primes, factors and common factors 2002-11-20
From Connie:
My son can't remember what a composite number is, what a prime number is and the explaination of factors and common factors. Help!
Answered by Penny Nom.
Why is 5 divided by 1/7 greater than 5 divided by 2/3? 2002-11-19
From Elizabeth:
  1. Without performing the division, explain why 5 divided by 1/7 is a number greater than 5 divided by 2/3.
  2. Is the least common multiple of two prime numbers always their product? Why or why not?

Answered by Diane Hanson and Penny Nom.
Prime numbers 2002-11-08
From Lonna:
Is 2 a prime number or not??
Why is 1 not considered a prime number?

Answered by Penny Nom.
Is it a prime? 2002-10-19
From JV:
6x to the third power plus 5x plus 15, is that prime or not prime, and whichever it is, how can you prove it? ya dig?
Answered by Claude Tardif.
Relatively prime 2002-10-04
From Natasha:
I really need help with this middle level math question. My little brother is asking me and I have no clue what the answer is. Explain what it means when two numbers are negatively prime. (?)
Answered by Kathy Nolan and Penny Nom.
Divisibility of 5 2002 2002-08-25
From Simon:
I need to ask you a question if 5 2002 and 3 2002 are divisible by 26.
Answered by Penny Nom.
Primes and square roots 2001-06-14
From Paul:
I have a bit of a math problem. It has to do with determining if a very large number is a prime. One method entails dividing the number by every smaller prime number. If any divide into it, it's not a prime. This would be a big job if the number was something like 400 digits long. Another way I read about was to take the square root of the number and test all the primes less than its square root. The explanation went like this: "When a number is divided by another number that is greater than its square root, the result is a number smaller than the square root. For example, the square root of 36 is 6. Dividing 36 by 2, a smaller number than 6, gives 18, a number that is larger than the square root. To prove that 37 is prime it is only necessary to divide it by primes less than 6, since if it had a prime factor greater than 6, it would have to have one less than 6 as well."

I understand the explanation, up to the last sentence. I fail to see the underlying logic. Why if a prime factor exists below the square does one have to exist above the square too? The number 40 can be divided by the prime 2, a number below its square root, but no other primes can do this above its square root. Have I missed something? What's the logic here?


Answered by Claude Tardif and Penny Nom.
Neither prime nor composite 2001-05-08
From Marc:
what 2 numbers are neither prime nor combitative?
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.
Two number theory questions 2001-01-30
From Richie:
i have two questions and they are:
  1. the product of three consecutive prime numbers is 7429. Find the product of the smallest and largest of these three integers.

  2. the least common multiple of two relatively prime positive integers, a and b, is 144. if a (a>or=2) is as small as possible, compute the value of b.

Answered by Penny Nom.
What number from 1 to 25 has the most factors? 2001-01-23
From John:
What number from 1 to 25 has the most factors?
Answered by Penny Nom.
A pair of numbers whose GCF is 28 2000-12-27
From John:
Name 2 different pairs of numbers whose GCF is 28.
Answered by Penny Nom.
Some prime conjectures 2000-12-24
From Tarrasita:
I was given some homework to investigate the following conjectures on prime numbers

1) There is at least one prime between consecutive square numbers.

2) Every prime except 2 and 3 is of the form 6n+1 where n is a natural number.

3) Any odd prime which is of the form 4n+1 is equal to the sum of two perfect squares.


Answered by Harley Weston.
Prime factorization 2000-12-13
From A student:
What is the prime factorization for 250 1296 and 2400
Answered by Penny Nom.
A zip code problem 2000-10-26
From Rob Mathis:
Find the zip code of a place in a county so that the product of it and the zip code of another place in another county of the same name, but in a different state, is an exact multiple of the number 123456789
Answered by Claude Tardif.
1234567890 2000-09-14
From Bradley Kloetzly:
Can you find two whole numbers, with the smallest possible difference between them, which when multipled together equal: 1234567890?
Answered by Harley Weston.
Five times a cube equals three times a fifth power 2000-07-05
From Harman Chaudhry:
Which is the smallest 10-digit number to be five times the cube of one number and also three times the fifth power of another?
Answered by Penny Nom.
How many zeros? 2000-04-09
From Greg Potts:
The natural numbers 1 to 25 are multiplied together (1 x 2 x 3x..24 x 25). How many zeros are there in the product of this multiplication?
a)6 b)7 c)5 d)10 or e)4?

Answered by Harley Weston.
2^32 + 1 2000-04-08
From Un Etudiant:
232 +1 can be divided by 641 , why?
Answered by Claude Tradif.
Symmetric Primes 2000-04-01
From Marlene Moore:
Hi...Im in 9th grade and am having a hard time figuring out symmetric primes. Heres the problem:

Find two pairs of symmetric primes of 20. Symmetric primes of 15?


Answered by Claude Tardif.
Division 2000-03-16
From Charday:
What is the easiest way to calculate the least number that can be divided evenly by all the numbers from 1 to 10.
Answered by Penny Nom.
10 000 000 = a x b 2000-03-06
From Spencer Jaffe:
What two numbers that don't end in zero, multiplied equal 10,000,000.
Answered by Claude tardif.
Factoring, primes, GCF and LCM 2000-02-27
From Ruth Kroek:
My son is in grade seven, he has to do a Factoring Booklet the areas covered are:
  • Prime #'s
  • Composite #'s
  • Rainbow Factoring
  • Finding Multiples (consecutive multiples)
  • Finding GCF of 2-3 numbers uning Rainbow factoring
  • Finding LCM of 2 numbers using consecutive multiples
  • prime factor trees
  • prime factor ladders
  • finding GCF of 2 numbers using Prime number Method
Although his text 'Math Power' gives some information, we are at a loss ..

Answered by Penny Nom.
Three factors 2000-02-21
From A parent:
Question from a parent helping a child, grade 4, with homework. Can a number have three factors? Name three numbers that have three factors.
Answered by Penny Nom.
Three algebra problems 1999-12-28
From Stephanie Branton:
  1. If P represents the product of all prime numbers less than 1000, what is the value of the unit's digit of P?

  2. Do any real numbers a and b exist such that: ln(a+b)=ln a + ln b? if so, what are they?

  3. Define a function by: f(x)=1/1-x where x is not equal to 0,1. what is f(f(f(a)))?

Answered by Harley Weston.
T-shirts 1999-04-04
From Valerie:
At a discount T-shirt shop the manager marked a special batch of T-shirts that originally sold for $2.00. When all the shirts sold the shop had collected $603.77.

How many shirts did they sell and what was the price per shirt?
Answered by Jack LeSage and Penny Nom.

Prime dates 1999-03-25
From Jessica Brown:
I'm asking how do you figure out all the prime numbers in a year and, whats the average amount of prime numbers per week.
Answered by Jack LeSage and Penny Nom.
Five Factors 1998-09-19
From Derek Yau:
To whom it may concern,

I have difficulty in getting the solution to the following question:

Find 5 numbers that have exactly 5 factors.

I got 16, 81 but couldn't find the rest. I believe that in order to have 5 factors, it has to be a square number. Isn't it true? I guess there may be a pattern to this.

Thanks for your help.
Derek Yau.
Answered by Penny Nom.

Divisors of 6n 1998-01-26
From James:
If n is a positive integer such that 2n has 28 positive divisors and 3n has 30 positive divisors, then how many positive divisors does 6n have?
(a) 32 (b) 34 (c) 35 (d) 36 (e) 38

Answered by Penny Nom and Haragauri Gupta.
Negative Primes. 1997-11-10
From Leah Zucker and Paul Michael:
I have received the following question via e-mail from my granddaughter: "Can negative numbers (like -7) be prime? If not, why not?"
Answered by Chris Fisher.
Two Questions 1997-10-28
From Melissa Kelley:
I would appreciate any help you could give me.
  1. Why isn't 1 a prime number?

  2. How can the absolute value of a number be negative?

Answered by Penny Nom.
Prime Numbers 1997-09-04
From Jack Bedard:
Hi. I have a real stupid question

What are prime numbers?

My name is Jack Bedard and I am in grade 5.
Answered by Penny Nom.

Divisibility of 2n choose n. 1996-09-24
From Kathy Doan:
Can you prove that "2n choose n" is not divisible by 3, 5, and 7 for infinitely many n?
Answered by Penny Nom.
How do you find out if a number is a composite or prime? 1996-09-16
From Trish Feenstra:
Hi my name is Trish Feenstra. In grade 8. How do you find out if a number is a composite or prime if it is big like 37 529? Reply soon got a test on Friday the 13th
Answered by Denis Hanson.
Prime numbers 1996-02-22
From Charles Hewitt:
I would apprecaite it if you could share with me any algorithm to determine whether a number is prime.
Answered by Penny Nom.
Deux nombres consécutifs 2010-01-18
From Janot:
Bonjour comment peut on faire pour démontrer que si deux nombres sont consécutifs, leur produit et leur somme sont premiers entre eux Merci de me mettre sur la voie , j'ai échoué avec Bezout.
Answered by Claude Tardif.
2^(2^1954) est-il premier? 2005-10-04
From Un eleve:
2(21945)+1 est-il premier?
Answered by Claude Tardif.
 
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