Numbers 1:2-4

2 Reckon ye up the sum of all the assembly of the sons of Israel, by their families by their ancestral houses, in the counting of names, every male, by their polls;

3 from twenty years old and upwards, every one able to go forth to war in Israel, ye shall number them by their hosts, thou and Aaron;

4 and with you, shall be one man for each tribe, each man, head of his ancestral house, shall be.