Numbers 1-3

The Census of Israel’s Warriors

[45] So all the numbered men of the sons of Israel by their fathers' households, from twenty years old and upward, whoever [was able to] go out to war in Israel, [46] even all the numbered men were 603,550. [Num 1:45-46 LSB]

Levites Not Numbered in the Census

Israel Camped by Their Standards

Priests and Levites

[12] "Now, behold, I have taken the Levites from among the sons of Israel instead of every firstborn, the first offspring of the womb among the sons of Israel. So the Levites shall be Mine. [13] "For all the firstborn are Mine; on the day that I struck down all the firstborn in the land of Egypt, I sanctified to Myself all the firstborn in Israel, from man to beast. They shall be Mine; I am Yahweh." [Num 3:12-13 LSB]

Responsibilities of the Priests

Redemption of the Firstborn