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Strings of characters 2015-12-28
From Ali:
If I have an app and offer a two, three and four digits name and it can be only number, letters or both?
I want to know how many options will I have for each?
For example
the two digits: aa, 11, a1 or 1a
the three digits: 111, a2a, 222
the four digits: 1111, 2ge3 or 1234
So if I used all the letters and all the numbers but nothing starts with a zero How can I calculate them separately? Or what's the result for each?
Thank you

Answered by Penny Nom.
6 character strings using 1, 5 and 9 2014-06-15
From Kevin:
How many 6 digit combinations (i.e., 159159) can be made from 3 different numbers (i.e., 1,5, and 9)? The numbers will obviously have to repeat. A link to a calculator that could list all the combinations would be helpful. I've come across these sites: http://textmechanic.com/Permutation-Generator.html, and http://textmechanic.com/Combination-Generator.html , but am not sure how to use them for my specific case. Thanks.
Answered by Penny Nom.
A cable around the Earth 2014-03-13
From fikile:
By how much must an equatorial cable be extended in order that it runs 1meter above the ground?
Answered by Penny Nom.
A string wrapped around three circles 2013-10-19
From Jim:
A recent puzzle ' find the length of a string around 3 touching 1 meter diameter circles ' gave this answer : the string touches 120 (or pi/3 meters) of each circle. Then 3(1+pi/3) = 3+pi meters is the required length. I do not see how it was determined that the string touches 120 or pi/3 meters?
Please explain . Thank-you , Jim

Answered by Penny Nom.
Factor strings 2013-10-14
From Jane:
What's a factor string? I'm confusey in the head.
Answered by Penny Nom.
If the earth was made of a ball of string 2013-09-18
From Tammy:
My 9 year old son asked me a question and I have no idea how to work it out! Please can you help?

If the earth was made of a ball of string and you unravelled the string how long would it be? Assuming the string is 5mm thick.

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 string around the world 2008-08-18
From Terry:
I heard this on T.V. and was wondering if it was true. Place a string around the world, you would need 25,000 miles of string. If you raised the string off of the ground by 1 foot all the way around. How much more string would you need?
Answered by Penny Nom.
A game with some strings 2004-01-22
From Trudy:
A boy holds 6 pieces of strings in his hands with the ends protruding above and below. The top ends are tied together in pairs and then the lower ends are tied together in pairs. What is the probabilty that the pieces of string are all joined in one loop?

What is the probability of obtaining two loops? Can you generalise this to solve the problem for 2n blades of grass?

Answered by Andrei Volodin and Penny Nom.
A rock on a string 2003-10-26
From A student:
a rock on a 4' string is rotated at 80 rpm. what is the linear speed in feet per second? in miles per hour?
Answered by Penny Nom.
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.



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