What does this mathematical rebus means ?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

You see me once in June, twice in November, and not at all in May. What am I?

Keyboard words are not in alphabetical order, Why?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

What has a ring but no finger?

What goes up but never comes down?

Before reading ahead, you must know the fact that only one of the people here is telling the truth.

A says that B is lying.
B says that C is lying.
C says both A and B are lying.

Can you find out who is speaking the truth?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

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