A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Can you find the missing piece of the Porsche?

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.

Can it be possible to build a house that has all its four walls facing towards the South?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

How can a man go eight days without sleep?

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?

When it is alive we sing, when it is dead we clap our hands. What is it?

Where do fish keep their money?

What month of the year has 28 days?