How many sides does a circle have?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

John was piloting a plane behind a car but was never able to overtake it. Why?

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

How many times can you subtract the number two from the number fifty?

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

Why 1729 is a magic number? Answer Logically.