What always comes into a house through the keyhole?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

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.

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

I have a mouth but I don't eat.
I have a bank but have no money.
I have a bed but i dont sleep.
I wave but have no hands.

Who Am I ?

A man is found dead with a knife in his back When the investigation is done. A chair lays beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?

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

Can you count the number of triangles in the given picture?

What you cannot hold but it is yours?