Albert Barnes Commentary Mark 6:40

"And they sat down in ranks, by hundreds, and by fifties." — Mark 6:40 (ASV)

In ranks. Literally, in the form of square beds in a garden. By square, regularly formed companies.

By hundreds, and by fifties. Some companies had a hundred in, and some fifty. We need not suppose that these were exactly formed, or arranged; but that this was about the number. The expression indicates a multitude. There were so many, that they sat down, by hundreds and by fifties, in separate companies, on the green grass.