3 business men go to a hotel, manager says £30 for a room, so they each pay £10. When they leave for their room the manager realises the room is only £25 so asks a member of staff to take £5 to the men. He decides the best way to split it is to give each man £1 and keep £2. Each man has now paid £9. 9x3=£27. The member of staff kept £2, 27+2=£29. Where did the other £1 go?