It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?

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

What has many keys but can’t open a single lock?

What makes this number unique: 8,549,176,320?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

Which is heavier: a ton of bricks or a ton of feathers?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?