This is an old problem…but here goes.
Three businessmen decide to save money on a business trip by sharing a hotel room. The men are charged $30 for the room. They each pay with a $10 bill and retire for the evening. The hotel manager then notices that she should have only charged the men $25 for the room. She gives the bellhop 5 one-dollar bills and gives him instructions to take the men the $5. On the way to the room, the bellhop decides that he will help himself to a $2 tip. (Five isn’t divisible by three anyway.) He gives the remaining money to the men, and they each take $1.
At this point, the three men have each paid $9 for the room. 3x$9 = $27. The bellhop has $2 in his pocket. $27 +$2 = $29.
Where is the missing dollar?
Click here for link to a site that provides an explanation (after you’ve tried for a day or two to figure it out on your own, of course.)