What is the fastest way to double your money?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

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?

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

Move four matchsticks to the below square to form three squares?

What will you call your mother's brother's brother-in-law?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Akbar called Birbal and asked him to draw a line on the floor. He asked Birbal to make that line smaller without erasing it. Birbal smiled and did it before Akbar could blink his eyes.

How did he managed to do it?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?