Three guys were on a road trip. One night, at 3:00 AM, none of them were awake enough to drive, so they checked into a hotel. The bellhop charged them $30 for a room. Each guy paid $10 for it. In the morning, the owner came in and told the bellhop that he overcharged for the room. It was

$25, so he was told to give the guys their change. The bellhop gave each guy a dollar, and kept two for himself. So at the end, each guy spent $9, and the bellhop had $2.
But, $9*3 = $27, plus the $2 the bellhop had. That makes $29, where is the other dollar?
Two answers are correct:
a) It's the 25th dollar in the cash register. OR
b (more correct)) There isnt a dollar missing. $9*3 = $27, MINUS the $2 the bellhop had = $25, which is the price of the room.