Project Euler is a site where you can try your hand at solving various mathematical problems. They are designed to be solved with simple programs. Many of them are too complicated to be strictly bruteforced however, and require more elegant solutions based on knowledge of the problem. You can check out more about it at http://projecteuler.net/
I am using these problems to attempt to get used to Python's syntax, which I find bizarre. I'm used to braces, semi colons, and all the whitespace I want. This also means that many of my solutions are sub optimal. I would rather code a slower program and use something new than use my existing math knowledge to make the problem easy to code.