I used to rent Braingames (the compilation VHS) from the local library all the time. And believe it or not, it actually helped me on a recent Math Exam in college Pre-Cal (okay, okay, it was a bonus question):
The test? Probability
The question? If you have a drawer with blue socks, red socks and greens socks, how many socks must you pull from this drawer to guarantee you have a matching pair?
The answer? Four. The answer fits for any problem like this. It's always one number higher than your choices.