A father's child, a mother's child, yet no one's son.

Who am I?

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

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

81 x 9 = 801. What must you do to make the this equation true?

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?

Krish is 45 years old and his mother Crishtina is 73 years old.

Can you find out how many years ago, his mother was three times his age?

What number do you get when you multiply all of the numbers on a telephone's number pad?

How many words can a pen with half refill write?

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.

What can go up a chimney down, but can’t go down a chimney up?