The enrollment of the priests was according to their fathers' houses; that of the Levites from twenty years old and upwards was according to their offices, by their divisions.
These are those who were numbered of the families of the sons of Merari, whom Moses and Aaron numbered according to the commandment of the Lord by Moses.
from thirty years old up to fifty years old, every one that could enter to do the work of service and the work of bearing burdens in the tent of meeting,