What is the coolest letter in the alphabet?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

If,

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

Then

4 / 5 = ?

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?

As we know that white starts the game of chess. Can you find the scenario shown in the picture below is possible when all the white pieces are at the original place while the black pawn is not as in the below picture?

Solve this riddle by finding the odd one out from the rest.

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 ?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

Can you place six X (crosses) in below board without making three in a row in any way ?