I have branches, but no fruit, trunk or leaves. What am I?

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

Find the missing number in the series below

13 -21 34 -55 ? -144

Why Aeroplane windows are round?

Here is a Swiss Cross. You have to make two straight cuts in the figure so that it is divided into four congruent pieces. Also, you should be able to join these pieces into a square then. Can you accept this challenge?

How can you make a TV, a bed, a dog, and a car liquid?

Prove that twice of ten is the same as twice of eleven.

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

Can anyone tell me a word in the English dictionary which has a silent 'z'?

Ten coins have been arranged as you can see in the given picture. In this arrangement, a triangle is formed pointing upwards. You have to invert the position of the triangle and make it point downwards while changing the position of 3 coins only. Can you do it?