Three friends went to a hotel. The bill was Rs 30/- Each one contributed Rs.10/-. The waiter took the bill to the cashier.

The cashier was happy & decided to give them a discount of Rs.5/- & asked the waiter to return them Rs.5/-.

Now the waiter was confused. How to distribute Rs 5 among 3 persons?

He kept Rs 2 in his pocket & gave one rupee to each one of the 3 persons.

So initially each one had contributed Rs.10. Now as they are given 1 rupee back, their contribution reduces to Rs 9.

They all contributed Rs 9 — that is 9×3=27 & 2 rupees are in the waiters pocket.

The total becomes 29. But they had paid Rs 30.

Where is the remaining 1 rupee?.