I have eight fingers and two thumbs but I do not live. What Am I?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

What you cannot hold but it is yours?

What goes through cities and fields, but never moves?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

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.

A father's child, a mother's child, yet no one's son.

Who am I?

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?

No one wants to have it, but if one got it, he does not want to lose it. What is It?