Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

What is full of holes but still holds water?

How many letters are in the alphabet?

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

Bopanna was working on a murder case when he received a message about the location of the murder weapon.
The message was encrypted as below.

"deb mitciv eht edisni neddih si nopaew redrum ehT"

Tell me the location of the murder weapon.

Where do fish keep their money?

How many letters are in the alphabet?

Who are the happiest people in IPL match?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?