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

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Why did Navjot Singh Sidhu put the new January calendar in the freezer

If you were to put a coin into an empty bottle and then insert a cork into the neck, how could you remove the coin without taking out the cork or breaking the bottle?

The following sentence is false. The preceding sentence is true.
Are these two sentences true or false?

The barber of Town shaves all men living in the town. No man living in the town is allowed to shave himself. The barber lives in that town. Who then shaves the barber of the town?

What is red and smells like blue paint?

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

What is both possible and impossible at the same time?