How Many
How Old
noun
This has the same meaning as the kanji, specifically the how many meaning. You know this because you ask "how many" and they answer "つ." This can also be used to ask how old someone is, but generally only for children's ages.
This word is usually written in kana in modern writing.
The reading comes from what you learned in the kanji, nice job.
その小づつみの中にリンゴが幾つ入っているか数えてもらえる？
Can you count how many apples there are in that parcel?
録音に適したマイクを幾つ知っていますか。
How many mics do you know of that are adequate for recording?
おじょうちゃんは幾つかな？
How old are you, little girl?