As a gift for Christmas, a wealthy family gives its children seventeen computer games.
The youngest child gets one ninth of the games, the middle child gets one third of the games and the eldest child gets one half of the games.
How are the games divided up, remembering you cannot have part of a computer game?
The family are a little stuck until they borrow a game from their neighbours. This allows: one ninth of 18 is 2, one third of 18 is 6 and one half of 18 is 9. Now, this adds to 2 + 6 + 9 = 17, leaving the spare game to give back to their neighbour!