Moses did not number the people but when God commanded him. We have here the families registered, as well as the tribes. The total was nearly the same as when numbered at mount Sinai. Notice is here taken of the children of Korah; they died not, as the children of Dathan and Abiram; they seem not to have joined even their own father in rebellion. If we partake not of the sins of sinners, we shall not partake of their plagues.
SDA Bible Commentary (limited)
Volume 1-7
4. From twenty years old. The previous census had been taken 38 years before, and those numbered were now dead (v.64).