5 items are filed under this topic.








Strings of characters 
20151228 

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
Ali Answered by Penny Nom. 





6 character strings using 1, 5 and 9 
20140615 

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/PermutationGenerator.html, and http://textmechanic.com/CombinationGenerator.html , but am not sure how to use them for my specific case. Thanks. Answered by Penny Nom. 





Factor strings 
20131014 

From Jane: What's a factor string? I'm confusey in the head. Answered by Penny Nom. 





Four digit "combinations" using 0124 
20130227 

From Ayana: What are all the possible four digit combinations using 0124. Please list them for me. Thank you. Answered by Penny Nom. 





A game with some strings 
20040122 

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. 


