enter

category

mathematics (field of study)

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter

to go in; to come in / 要る: to be necessary, to be required

to enter, go into, get into a place or a thing / to join a group or organization / to be contained (in), to be included (in) / to be a member of a group, set, category

(mathematics) pure mathematics

applied mathematics

mathematician

Alternative spelling of 組合せ数学 (“combinatorics”)