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

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

What am I?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you identify if it's a murder or a suicide ?

I am an eight letter word and I am a computer terminology.
The second, third and fourth letters make an animal.
The fourth, fifth, sixth, seventh and eighth letters make a weapon.
The first, second, third and fourth letters can be taken as an outcome of any exam.
The fifth, sixth, seventh and eighth letter combine to form a high end typing software.

Can you tell who am I ?

What 5-letter word typed in all capital letters can be read the same upside down?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?