Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Which alphabet letter is a question?

What does it mean?

What is red and smells like blue paint?

Replace the question mark with the number below given a simple math problem.

A man plots the murder of his wife. His plan is full proof. Nobody saw them leaving their house. He stabbed her with a knife while driving. She died on the spot. He threw her body in a valley. He threw the knife carefully wiping his finger prints on a random garbage bin. Then he went back to his home and no one was watching him this time as well.

After an hour, he was called by the local police department who informed him that his wife was murdered. They asked him to reach the scene of crime immediately. But as soon as he arrived at the crime scene, he was arrested by them.

How did the police know that he himself is the murderer?

I have an eye but still cannot see.

Who am I?