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

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

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?

What has many keys but can’t open a single lock?

I’m orange, I wear a green hat and I sound like a parrot. What am I?

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?