numeral · a particular way of doing things or a set pattern of behavior

他在管理员工方面很有一套。

numeral · a classifier combination used to quantify a collection or suite of items, in this context specifically referring to an apartment unit.

我刚租了一套公寓。

the same old stuff, clichéd talk, or conventional behavior

少跟我来这一套，我才不信呢。

a suit, collection, or complete group of objects of the same kind

他买了一套新西装。