Numbers 2:9, 16, 24

The total of the numbered men [in the three tribes on the east side] in the camp of Judah was 186,400, by their armies. They shall move out first [on the march].

The total of the numbered men [in the three tribes on the south side] in the camp of Reuben was 151,450, by their armies. They shall move out second [on the march].

The total of the numbered men [of the three tribes on the west side] in the camp of Ephraim was 108,100, by their armies. They shall move out in third place.