I know a nine-letter word having only one vowel.
Do you ?

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

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Can you count the number of matches in the picture below ?

P is the father of Q and S is the son of R. T is the brother of P and has a daughter U. If R is the sister of P, then what is the relation between U, Q and S?

What four weights can be used to balance from 1 to 30 pounds?

If eleven plus two equals one, what does nine plus five equal?

This is a most unusual paragraph. How quickly can you find out what is so unusual about it? It looks so ordinary, you'd think nothing was wrong with it. Actually, nothing IS wrong with it. But it is not as ordinary as you might think. If you think about it for a bit, you will find out why it is truly so unusual. So what is it? What is so unordinary about this paragraph?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?