Numbers opens on the first day of the second month, in the second year after the exodus, as Yahweh speaks to Moses in the wilderness of Sinai, in the Tent of Meeting. Israel had received the law and built the tabernacle. Now they needed to be organized for the journey to the promised land. God commanded a census of every male from twenty years old and upward, all who were able to go out to war.
A leader from each tribe stood with Moses and Aaron, from Elizur of Reuben to Ahira of Naphtali. The registration was by families and fathers' houses, and each name was declared. Judah had 74,600, the largest tribe, while Manasseh had the smallest number. The grand total was 603,550. This multitude showed that God's promise to Abraham, to make his offspring as the stars, was being fulfilled.
The Levites were deliberately left out of the military count. God appointed them over the tabernacle of the covenant and all its furnishings. They would carry it, care for it, and camp around it, so that there would be no wrath on the congregation. Thus the children of Israel did. According to all that Yahweh commanded Moses, so they did. The book begins with obedience, though it will later record failure and God's patient faithfulness.