What Adam and Eve do not have but the rest of the people have?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

What is the centre of gravity?

How can you make number one disappear by adding something to it?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

I was born in a small house and I live in it all alone. No windows and no doors have been assigned to my house. The only way I can go out is by breaking through the walls of my house.

Who am I?