Why is 6 afraid of 7?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

When is the top of a mountain similar to a savings account?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

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

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Can you solve the rebus below?

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?