There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

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?

Find the missing number in the sequence below:

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

I always drive my customer away.

Who am I?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?