If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.

Why is it very easy to weigh a fish?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

There is an English word that can be used up to four times in a row without modifying the spelling and form a valid grammatical sentence.

Do you know what word is that?

I cannot talk, but I always reply when spoken to. What am I?

Move four matchsticks to the below square to form three squares?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

What happened when the wheel was invented?

Can you make the number 24 by utilizing the numbers 1, 3, 4 and 6? You must use one number only one time and you can use mathematical operation symbols anytime anywhere.

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?