Three men go into a restaurant and each order a snack costing £10
When the food arrives each gives the waiter a £10 note in payment.
The waiter takes the money to the cashier who says there is a £5
discount on orders of £30 and gives the waiter five £1 coins to
return to the men.
The waiter decides that five does not divide by three so he pockets
£2 and gives £1 to each of the diners.
Thus each of the diners has paid £9 for his meal.
Three times nine equals twenty seven which plus the two pounds the
waiter took is twenty nine.
What happened to the other pound?