You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

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

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Five thieves looted a bank and they ran away in a car. The bank staff informed the police and they began the search of their car in their jeep. They found them on a road and chased them eventually catching them. The light that is used to fill the number plate was broken on the thieves' car. Also, the headlights of the jeep police were not working. How were the police able to catch the thieves then?

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

There is something which you can be arrested for attempting but not for successfully completing.

If you say my name, I will no longer exist. What am I?

If eleven plus two equals one, what does nine plus five equal?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10