Brain Teasers

I have no doors, but I have keys. I have no rooms, but I have space. You can enter, but you cannot leave. What am I?

What can you find in a minute or an hour but never in a day or a month?

What are the next three letters in the following sequence? 

J, F, M, A, M, J, J, A, __, __, __

I am an odd number. Take away a letter and I become even. What number am I?

What has a mouth but cannot eat and runs but has no legs?

What is harder to catch the faster you run?

A man stands on one side of a wide river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

You are in a world where there is only one law. There is a mirror, but no reflection. There is pizza with cheese, but not sausage. There is pepper, but no salt. There is a door, yet no entrance or exit. What is the law?