Oznayim la'Torah: To teach us that, even though, as opposed to the leaders of the other three Degalim - Yehudah, Efrayim and Dan - Reuven did not exceed in numbers the other two tribes in his Degel, nevertheless he was appointed leader of his Degel on his own merit, because he was the firstborn.

Moshav Zekenim: There is a 'Yud' in place of a 'Nun' (the Gematriya is forty less), to hint that all forty years in the Midbar, Yehudah's bones were rolling around in his coffin. All forty years, he was not tranquil.