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

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

You Throw The Outside, Cook The Inside
Eat The Outside, Throw The Inside.

What Is It?

A monk has a very specific ritual for climbing up the steps to the temple. First, he climbs up to the middle step and meditates for 1 minute. Then he climbs up 8 steps and faces east until he hears a bird singing. Then he walks down 12 steps and picks up a pebble. He takes one step up and tosses the pebble over his left shoulder. Now, he walks up the remaining steps three at a time which only takes him 9 paces. How many steps are there?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

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?

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.

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

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