13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

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?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

What can you catch but never throw?

Replace the question mark in the picture below.

Why despite killing dozens of people Charley and Wilma were not punished?

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

What is more useful when it is broken?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

What is always in front of you but can’t be seen?