How many sides does a circle have?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

Why 1729 is a magic number? Answer Logically.

What demands an answer, but asks no questions

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

Fate has decided that you will only be pleased to meet me when you need me

Maybe that is why, when I am working, I start working

However annoying I may be to the regulars, the little ones are always inspired

I will always be waiting if you try to reach me

How many of you can guess my name, let me see

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

How many times can you subtract the number 5 from 25?

Samuel was out for a walk when it started to rain. He did not have an umbrella and he wasn't wearing a hat. His clothes were soaked, yet not a single hair on his head got wet. How could this happen?