If a wheel has 54 spokes, how many spaces are there between the spokes?

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

What is so fragile that saying its name breaks it?

You know three triplets: Frank John and Wayne (need to return your money). Frank always tells the truth while John and Wayne always lie. You meet one of them on the road and can ask him a three-word question.
Which question, will you ask?

You need to move three matchsticks to form three squares. Can you do it?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. 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 family is trapped in a jungle. There is a bridge which can lead them to safety. But at one time, the bridge can only allow two people to pass through. Also, all of them are afraid of the dark and thus, they can't go alone.

Father takes 1 minute to cross, the mother takes 2 minutes, the son takes 4 and the daughter takes 5 minutes. While crossing the time taken will be according to the slower one. How can they all reach the other side in the minimum possible time?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?