try this one...

3 men go into a hotel, they each pay 10$. so in total they pay 30.the manager realizes he over charged them so he give a bellboy 5$ to give back to the 3 men...the bellboy thinks to himself you can't split 5$ 3 ways so he steals 2$ and gives them each 1$. now they have all paid 9$ 9X3=27 ......27=2 in bellboys pocket=29 .

one dollar is missing?