Which number should replace the question mark?

You need to move three matchsticks to form three squares. Can you do it?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

What is the difference between a jeweller and a jailer?

What part of Turkey has the most feathers?

Next Number in the Series,

5, 16, 49, 104, ?

What came first, the chicken or the egg?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

How many squares, of any size, can you find on this chessboard which do not contain a Rook?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?