You have a thousand Re. 1 coins with you. You have ten bags with you and you can put any number of coins in each of the bags. The condition is that if someone asks you for any amount between 1 and 1000, you must be able to give that amount by just giving the bag (you are not allowed to open the bag and give coins).

How will you do it ?

First Bag = 1 Coin

Second Bag = 2 Coins

Third Bag = 4 Coins

Fourth Bag = 8 Coins

Fifth Bag = 16 Coins

Sixth Bag = 32 Coins

Seventh Bag = 64 Coins

Eighth Bag = 128 Coins

Ninth Bag = 256 Coins

Tenth Bag = Remaining Coins.

Now think of any amount between 1 and 1000 and you will be able to give it by using bags (without opening them)