How can a man go eight days without sleep?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

With the help clues provided in the image, can you find the 5 digit key?

Who has married many women but was never married?

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

Where do fish keep their money?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

I inserted a coin in a bottle and closed its mouth with the help of a cork. Now, I was able to take the coin out from the bottle without taking out the cork or breaking the bottle. Can you tell me how I did it?

Let's play a word game. Following are some meaningless words that can be completed by adding random letters on either side of the word.

For example, the word "rdo" can be formed into "pardon".

Using the same technique, can you complete the given words?
ecalc
airb
rinci
tibac
uidel
gorit
igna
eyho

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title