What brings you down but never up?

There is an English word that can be used up to four times in a row without modifying the spelling and form a valid grammatical sentence.

Do you know what word is that?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

What can you deduce from the following BrainBat?

CRY
LMKI

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

What number when divided in half becomes zero?