For programmers out there who want to refresh their math skills:

Project Euler - http://mathschallenge.net/index.php?section=project

From the website:

Project Euler

Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems. Please be warned that the problems are challenging and you are unlikely to make much progress if you have no knowledge of programming. Having said that, this is both the perfect environment and opportunity to learn new techniques and refine your programming skills.

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Please note that each problem is designed according to a "one-minute rule", which means that although it may take several hours to design a successful algorithm with more difficult problems, an efficient implementation will allow a solution to be obtained on a modestly powered computer in less than one minute. Of course solving a problem is the ultimate goal, but if you consider yourself a skilled programmer/problem solver you may like to retry some of the challenges that took longer to solve on your first attempt.

A forum is available as an opportunity for users to discuss strategies used in solving the problems, with each problem designated its own thread. However, you will only be able to gain access to the thread once you have solved the problem.
Try your wits guys!