This Brain Game is really a question-answer, almost like trivia. And while you may have heard the answer before, coming up with it requires brainwork, not recall or knowledge. So if you're close - say, within five - I'd certainly consider your answer correct.

How many people
have to be together in a room
before there is at least a 50 percent chance
that two of the people in that room
will share the same birthday?

Click here for the answer.

Answer: Twenty-three. If you want to see the numbers crunched, there's a detailed explanation here.