The tribe of Ephraim - forty thousand and five hundred - Ephraim, as he was blessed beyond his eldest brother Manasseh, Genesis 48:20, so here he is increased by thousands more than Manasseh, and more than the whole tribe of Benjamin, and his blessing continued above his brother, Deuteronomy 33:17. And thus the prophecy, Genesis 48:19, was fulfilled: His younger brother (Ephraim) shall be greater than he, (Manasseh). No word of God can possibly fall to the ground: he alone sees the end from the beginning; his infinite wisdom embraces all occurrences, and it is his province alone to determine what is right, and to predict what himself has purposed to accomplish.
The enrollment, being taken principally for military purposes (compare Numbers 1:3, Numbers 1:20), would naturally be arranged by hundreds, fifties, etc. (cf. 2 Kings 1:9, 2 Kings 1:11, 2 Kings 1:13). In eleven tribes the number enrolled consists of complete hundreds. The difference, in this respect, observable in the case of the tribe of Gad here Numbers 1:25, and of the tribe of Reuben at the later census Numbers 26:7, is probably to be accounted for by the pastoral, and consequently nomadic, habits of these tribes, which rendered it difficult to bring all their members together at once for a census. Judah already takes precedence of his brethren in point of numbers (compare Genesis 49:8 note), and Ephraim of Manasseh (compare Genesis 48:19-20).