do a number on

call someone's number

To focus on someone, asking them to prove themselves.

have one's number on it

To be destined for someone.

have someone's number

To understand a person's character, capabilities, or situation.

look for number one

Alternative form of look out for number one.

look out for number one

To act in one's own interests; to act in a manner advantageous primarily to oneself.

lose the number of one's mess

To die, to perish.

number games

A numbers game: the use of inappropriate statistics (numbers) to reflect a desired result (usually misleading).

number one

First; foremost; best, often used after its headword.