Numbers 3:28
The males who were numbered, every male from a month old and upward totaled
Numbers 3:7
They shall carry out the duties for him and for the whole congregation before the Tent of Meeting, doing the service of the tabernacle.
Numbers 3:31
Now their responsibilities involved the ark, the table [on which the bread of the Presence was placed], the lampstand, the altars, the utensils of the sanctuary with which the priests minister, and the curtain, and all the service concerning them.
Numbers 4:35-36
from thirty years and upward even to fifty years old, everyone who enters the service to do the work in the Tent of Meeting (tabernacle);