(idiomatic, colloquial) Informal greeting roughly equivalent to How are you? or How's it going?

(idiomatic) An informal greeting, not requiring a literal response. In form a question, and thus followed by a question mark. Typical responses include:

unspecified number / what number

(interrogative) To what degree; to what extent.

(UK, slang, obsolete) you what? huh?

Synonym of what about

(interrogative) What amount or quantity (of something stated or implied). / (specifically, when referring to the cost of an item) What amount of money.

Used to inquire about the weather. / (by extension, idiomatic) Indicating a change of subject to unimportant topics.

(idiomatic, informal) Why; why is it; for what reason or purpose; due to what cause?

(colloquial) Alternative form of how about