It's that time again, and I'm running out of good ones so I must resort to one of my least favorites,

Achilles decides to race a tortoise. Because he runs ten times as fast as the tortoise Achilles gives the tortoise a 100 meter head start. By the time Achilles runs 100 meters, the tortoise has moved ahead 10, by the time Achilles has ran 10 more, the tortoise has moved one, by the time Achilles moves 1 meter, the tortoise moves 0.1 meter. When does Achilles pass the tortoise?

This is the first of Xeno's paradoxes, I suggest you look them up some time.