Are you asking how many combinations there are of letters and numbers? You don't need a big fancy program to do that, I'll get you started. There are a total of 26 letters right? And 10 numbers, so you have a total of 36 things to choose from. You have to know if order matters or not. For example, is ABC the same as CBA, or does it count as two different combinations. If it counts as two different combinations, then you want to do: 36P1 + 36P2 + 36P3...36P8, because you have 36 things to choose from, and you want to know how many different combinations you can have with 1 character, 2 characts, 3 character and so on till 8. If you don't know what 'P' means, well, you have some searching to do. If you have a graphing calculator, search around for a bit on it, you'll find something that says "nPr" that's what you want. If you have to do it by hand, search on google for "combinatorics" + "p", or something of that nature. Hope that helps.