A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

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.

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

The more you take me, the more you leave me behind.
Who Am I?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

A generous owner of a company decided to give a bonus of $45 to every man and $60 to every woman on his birthday. But only one-ninth of the men and one-twelfth of the women were present to take the bonus.

Can you calculate the amount of money the owner spent if there were 3552 employees?

Can you spot what's wrong with the following sentence?

PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.

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?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?