There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

When is the top of a mountain similar to a savings account?

What does this rebus means ?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Why do we preferably have round manhole covers and not square ones?

What number divided by 4 is the same as that number minus 4?

The more of this there is, the less you see. What is it?

what does the below rebus means?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?