Which number in a sequence; asking for the position or rank in order.
クラスであなたは何番目ですか？
What is your position (number) in the class?
彼女は会議で何番目に発表する予定ですか？
Which position is she scheduled to present in the meeting?
これが彼の作品の何番目のシリーズですか？
Which installment in the series is this of his works?