Replace the question mark with the correct number below.

Jack have ten pairs of black socks, eight pairs of white socks and seven pairs of green socks. Everything is mixed in a draw. As there is no light he were not able to identify the colour of the socks. How many of the socks did he want to take to match one pair

What do you see in the image below

An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

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 ?

What came first, the chicken or the egg?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?