Which floor? Used to ask about the floor number of a building or destination (e.g., in an elevator).
すみません、この会社は何階ですか？
Excuse me, which floor is this company on?
エレベーターで何階まで行きますか？
Which floor (shall I take you to) in the elevator?
図書館はビルの何階にありますか？
Which floor of the building is the library on?