Which number should replace the question mark?

Our product and our sum always give the same answer. Who are we?

Can you start the fire using two pieces of wood?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

What English word has three consecutive double letters?

What Does this text mean:

important=important

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

A man was driving a black truck. His lights were not on. The moon was not out. A lady was crossing the street. How did the man see her?

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