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?

How many bananas can you eat if your stomach is empty?

What do you see in the image below

Forwards I am heavy, backward I am not. What am I?

How can one talk without saying a single word?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

Can you find the key in the picture below?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?