How many people are on board?
Jōkyaku wa nan nin desu ka.
topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis
what; how many; you-know-what; that; whatsit; what's the expression; what do you call them; what?; hey!
-ian (e.g. Italian); -ite (e.g. Tokyoite); indicates nationality, race, origin, etc.; -er (e.g. performer, etc.); person working with ...; indicates expertise (in a certain field); (usu. in compound words) man; person; people
indicates a question (sometimes rhetorical); or; whether or not; some- (e.g. something, someone); indicates doubt, uncertainty, etc.; emphatic prefix; suffix forming adjectives or adverbs; in that way