(combinatorics) factorial

(music) chromatic scale

Synonym of もこし (mokoshi): a pent roof (below the true roof of a pagoda, etc.); a mokoshi

what floor?

upstairs; specifically, the floor above

a floor or storey in a building

see you later (said by a person staying, a stock phrase required by the Japanese etiquette, lit.: (after) going, come back)

行っていらっしゃい: alternative form of いってらっしゃい (itterasshai)

twenty; 20

two days, a two-day period / the second day after some set point in time / the second day of the month