3 men walk into a restaurant with 25 coins each and order food.
The bill is 72 coins.
The 3 men pay their 25 coins each to the waiter and ask him to return quickly with the 3 coins change.
The owner discounts this bill to 70 coins.
The waiter on his way back keeps 2 coins, and gives each of the men their 1 coin. So each man has finally paid 24 coins each.
So the total coins accounted for is - 2 kept by waiter + 24x3 paid by men = 74 coins
Where is the missing 1 coin?