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.

John is the son of Jacob.
So,
Jacob is the_____of John's father?

What always comes into a house through the keyhole?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

Why is it very easy to weigh a fish?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?