Three men agree to share a cab from the airport into town. When they arrive, the meter reads $25. Each man gives the driver a $10 bill. She hands them five $1 bills as change. Each man takes one of the $1 bills. They give the driver the remaining two $1 bills as a tip.

Each man has now spent nine dollars and the driver has two dollars for a total of $29. Where is the other dollar?

Your challenge is to explain this paradox.