Three men check into a hotel room that is $30 for the night.  Each pays $10 and they go to their room.  The person at the front desk realizes he overpriced $5 for the room and wants to give their money back.  THe money is given to the bellhop but the bellhop realizes that it could not be split evenly so he decides to give each man back a dollar and keep two dollars to himself.  So if each man actually paid $9 and 9 x 3 is 27 and the bellhop kept $2 where is the extra dollar?