from thirty to fifty years old, counting everyone who comes to serve in the work of the Tent of Meeting.
KJV
From thirty years old and upward even unto fifty years old shalt thou number them, every one that entereth into the service, to do the work of the tabernacle of the congregation.
ASV
from thirty years old and upward even unto fifty years old shalt thou number them, every one that entereth upon the service, to do the work of the tent of meeting.