Question: what is the chance of someone having the same birthday?
Answer: In a room of just 23 people there's a 50-50 chance of at least two people having the same birthday. In a room of 75 there's a 99.9% chance of at least two people matching. Put down the calculator and pitchfork, I don't speak heresy. The birthday paradox is strange, counter-intuitive, and completely true.