Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

What is black when you buy it, red when you use it, and gray when you throw it away?

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.

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

What building has the most stories?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

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

Who am I?