Numbers 3:15
3:15 “Number the Levites by their clans and their families; every male from a month old and upward you are to number.”
Numbers 3:40
The Substitution for the Firstborn
3:40 Then the Lord said to Moses, “Number all the firstborn males of the Israelites from a month old and upward, and take the number of their names.
Numbers 1:49
1:49 “Only the tribe of Levi you must not number or count with the other Israelites.
Numbers 15:12
15:12 You must do so for each one according to the number that you prepare.