I am an odd number. Take away a letter and I become even. What number am I?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

What is the coolest letter in the alphabet?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

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?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

How many times in a given day, minutes and hour clock comes in a straight line ?