Three guys go to a motel to rent a room for the night. The clerk tells them the room cost $30.00. Each guy ponies up $10.00 and they go to their room.

Then the clerk realizes there’s actually a special going on and the room is only $25.00 so he summons the maid, gives her five $1.00 bills and tells her to give the guys a refund.

On the way to the room, the maid starts wondering how she’s supposed to divide five $1.00 bills among three people. Then she decides to just pocket 2 bucks and give each guy one dollar and they’ll never know what the discount really was.

She refunds each guy a buck, so they paid 9 bucks each for the room.

9 x 3 = 27.

27 + the two dollars the maid pocketed is 29.

Where is the 30th dollar?