What is the fastest way to double your money?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

Find the missing letter in the last circle logically in the given below picture.

When monkey rotate the gear, which mark will be hit 1 or 2 ?

Imagine you are in a room with no windows or doors. How will you get out?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

A B C D E F G H

These are the letters given to you. Now you have to find out the letter that comes two to the right of the letter which is immediately to the left of the letter that comes three to the right of the letter that comes midway between the letter two to the left of the letter C and the letter immediately to the right of the letter F.