So Moses, Aaron, and the leaders of Israel numbered by their clans and families all the Levites
We have here a particular account of the numbers of the three families of the Levites respectively, that is, of the effective men, between thirty years old and fifty. Observe, 1. The Kohathites were, in all, 8600 from a month old and upwards; but of these there were but 2750 serviceable men, not a third part.
Commenting on Numbers 4:34-49
Num 4:34-48 Completion of the prescribed mustering, and statement of the number of men qualified for service in the three Levitical families: viz., 2750 Kohathites, 2630 Gershonites, and 3200 Merarites - in all, 8580 Levites fit for service: a number which bears a just proportion to the total number of male Levites of a month old and upwards, viz., 22,000.
Commenting on Numbers 4:34-48