Numbers 1:18

18 And they gathered (them together) in the first day of the second month, and they told them, (or they totalled them,) by kindreds, and houses, and families, and heads, and names of each by themselves, from the twentieth year and above, (And they gathered them together on the first day of the second month, and they listed, or they registered, them by their kindreds, and houses, and families, and heads, and their names, from twenty years of age and older,)

Numbers 1:18 Meaning and Commentary

Numbers 1:18

And they assembled all the congregation together on the first
[day] of the second month
The month Ijar, as the Targum of Jonathan, answering to part of April and May: this was done on the selfsame day the Lord spake unto Moses about this affair, ( Numbers 1:1 ) ; so expeditious were he and Aaron in doing the will of God:

and they declared their pedigrees;
either Moses and Aaron, according to Aben Ezra, who inquired when they were born, because of the computation of twenty years; and then their birth was wrote down, as he says; or rather the people declared their pedigrees, of what tribe, family, and house they were, who their parents, when born, and so, of course, how old they were; Jarchi interprets it, they brought the books of their genealogies, and witnesses to confirm the birth of everyone of them, to show their genealogy according to their tribe; nor is it at all unlikely that every family and house, or master thereof, kept a register of those born to him in it, whereby their age could be ascertained as well as pedigree:

after their famines, by the house of their fathers, according to the
number of their names, from twenty years old and upwards, by their
poll:
that is, every tribe gave an account of the families in it, every family what houses were in it, and every house what number of males were in it, and of what age; and such were numbered who were twenty years old and upward.

Numbers 1:18 In-Context

16 These were the noblest princes of the multitude, by their lineages, and kindreds, and the heads of the host(s) of Israel, (These were the noblest leaders of the multitude, by their tribes, and kindreds, and the heads of the armies of Israel,)

17 the which princes Moses and Aaron took, with all the multitude of the common people. (which leaders Moses and Aaron took, along with all the multitude of the common people.)

18 And they gathered (them together) in the first day of the second month, and they told them, (or they totalled them,) by kindreds, and houses, and families, and heads, and names of each by themselves, from the twentieth year and above, (And they gathered them together on the first day of the second month, and they listed, or they registered, them by their kindreds, and houses, and families, and heads, and their names, from twenty years of age and older,)

19 as the Lord commanded to Moses, (and so he numbered them there in the Sinai Desert).

20 And of Reuben, the first begotten of Israel, were numbered, in the desert of Sinai, by their generations, and families, and houses, and by the names of all the heads, all thing that is of male kind, from twenty years and above, of men going forth to battle, (And so the sons of Reuben, the first-born of Israel, were listed by their generations, and families, and houses of their kindreds, with the names of all who were twenty years of age and older, and all the men who could go forth to battle numbered)