In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

Which of the below owl is odd one out?

Replace the question mark in the picture below.

What is the fastest way to double your money?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

What is full of holes but still holds water?

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

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?