Numbers 4:33-37

This is the service of the families of the sons of Merari, according to all their service in the tent of meeting, under the direction of Ithamar the son of Aaron the priest.”

So Moses, Aaron, and the leaders of the congregation counted the sons of the Kohathites by their families and by their fathers’ households,

from thirty years old and upward even to fifty years old, everyone who could enter the service for work in the tent of meeting.

Their numbered men by their families were 2,750.

These were the numbered men of the Kohathite families, everyone who was serving in the tent of meeting, whom Moses and Aaron counted according to the commandment of the Lord through Moses.