Three friends have a meal in a restaurant. The waiter arrives with the bill, which is thirty dollars, and the friends put in ten dollars each to cover it. When the waiter leaves the able, he finds that he has overcharged them – the bill for the meal should have been twenty five dollars – so he finds five one dollar bills in change. Now being a slightly dishonest waiter, he decides to give the friends one dollar each, so they end up paying twenty seven dollars between them, and he pockets the remaining two dollars. But twenty seven dollars plus two dollars equals twenty nine dollars, not thirty. Where has the extra dollar gone?
Comment with your ideas/answers and I will reveal the answer at somepoint!
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The tales of a girl 
After having being asked by a friend who doesn’t comment directly onto my blog, here is the solution:
The numbers where never supposed to add up to $30, but to $25, since that is the total amount added to the till. And $9 + $9 + $9 – $2 = $25.
Hope you enjoyed!