What has to be broken before you can use it?

The dirtier I get, the whiter I look. Who am I?

This is a most unusual paragraph. How quickly can you find out what is so unusual about it? It looks so ordinary, you'd think nothing was wrong with it. Actually, nothing IS wrong with it. But it is not as ordinary as you might think. If you think about it for a bit, you will find out why it is truly so unusual. So what is it? What is so unordinary about this paragraph?

How can you take 2 from 5 and leave 4?

You enter your friend's room. He is not in his room. Although you see that on the bed there are two dogs, five cats, two giraffes and three pigs. Also, a couple of chickens and ducks are flying in the room.

Calculate the number of legs standing on the floor.

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

If a wheel has 54 spokes, how many spaces are there between the spokes?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

Before Mount Everest was discovered, what was the highest mountain in the world?

There are four 3-link chains. All you have to do is join them into a big 12-link chain. For joining two closed links, one of the links must be cut and placed onto the other link for closing.

How many minimum links will you have to cut to make the big chain?