What is the centre of gravity?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

Out of the nine cats that you can see in the picture, there are only two that are completely identical. Can you find them out?

I have branches, but no fruit, trunk or leaves. What am I?

A wealthy man lives alone in a small cottage. Being partially handicapped he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When a police officer arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?

Our product and our sum always give the same answer. Who are we?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

A man dies of old age on his 25 birthday. How is this possible?

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?