Math, for fun!

My recent attempts at programming have inspired me to try to get better at it. This is by no means new, but I've been working at solving the problems in Project Euler. It's a collection of math problems which you typically have to write some sort of program to solve. After you complete a problem you get access to a forum where people are discussing the problem. In the ones I've seen so far, there's a bunch of people discussing various ways to code the problem and some math genius who solved it just with math theorems. I'm up to problem 5.