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

I am the fastest animal but cannot climb the tree. What am I?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?

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 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?

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

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

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