The Disappearing Dollar

Three people check into a hotel. They pay $30 to the manager and go to their room. The manager realizes that the room rate is only $25 and gives $5 to the bellboy to return. On the way to the room the bellboy reasons that $5 would be difficult to share among three people, so he pockets $2 and gives $1 to each person. Now, each person paid $10 and got back $1. So they paid $9 each, totalling $27. The bellboy has $2, totalling $29.

What disappearing dollar? The room was $25. Each person paid $9, so they paid $27 for the room. Note that they overpaid for the room by $2. The $2 is in the bellboy's pocket!