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

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

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

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

I’m tall when I’m young, and I’m short when I’m old. What am I?

Which point will the car reach to go out?

Give it food and it will live; give it water and it will die.