Replace the question mark with the correct number.

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Outside a tattoo artist's shop, there was a signboard which read 'I make tattoos on only them who do not tattoo themselves'.

Reading it what do you think, does the tattoo artist tattoo himself?

Which digit occurred maximum times between the number 1 and 1000?

Using Only Five 5's and any mathematical operator make sum as 37

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

Consider all the numbers between 1 and 1 million. Among all these numbers, there is something very special about the number 8 and the number 2202. What is it?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?