In the Torah portion of Bamidbar we learn that G‑d commanded Moshe to take a census of the entire community by tribes.1 G‑d also told Moshe that while conducting this census “alongside him there shall be one man for each tribe.”2
Rashi explains that Moshe was instructed, “that when you count them, there shall be with you the princes of each individual tribe.” Thus, each tribal leader assisted Moshe not only in counting his own tribe, but in tallying the other tribes as well.
Who’s Counting?
The general objective of this census — counting the Jews in order to know their overall number — required that it be done by someone connected to all Jews equally. Moshe fit that bill perfectly. Accordingly, it would have sufficed for Moshe to conduct this count single-handedly, as he had previous counts.
The singular aspect of this count — that of first counting each tribe separately — required that the leader of every tribe take part in the count of his own tribe. But why was it necessary for the tribal leaders to assist in the count of the other tribes as well?
At the very beginning of the Torah portion, Rashi explains that because the Jewish people were very dear to G‑d, He counted them frequently. By doing so, G‑d revealed their qualities. As the Shaloh explains:3 counting the Jewish people gave them importance; it made them “an object worthy of numeration — that cannot become nullified.”4
Individual Yet Part of One Whole
The previous counts, in which all Jews were numbered as one entity — revealed the Jews’ general qualities and endearedness that transcends individual differences: the essential quality of the Jewish soul, in regard to which all Jews are exactly alike.
The count in the Torah portion of Bamidbar was intended to reveal the Jews’ individual merits as well. This is why in the latter count each tribe is tallied separately, for each of the 12 tribes had its own distinctive lifestyle, manner of Divine service, etc.
Yet, even while considering the particular qualities of the individual, every Jew remains a part of a single whole. This indicates5 that there was an aspect in this count in which all were equal — notwithstanding that they were counted according to their particular qualities and merits.
We are thus presented with an anomaly: Although this count was connected with the particular qualities of individual Jews — with the inevitable result of highlighting those disparate qualities and merits — nonetheless, every Jew was counted as equal to all other Jews.
The reason for this is the following: Counting the Jews in order to reveal the particular merits of each — counting according to tribes — not only served to emphasize individual qualities in and of themselves, but these qualities taken as a whole comprise one totality — the Jewish people.
It was thus necessary for the tribal leaders to be involved in the census of the other tribes as well, for it was necessary to remind them that their individual tribe constituted part of the Jewish people as a whole.
Based on Likkutei Sichos Vol. XXIII pp. 3-7.

This is an honest truth: I have never been rich, nor have I ever been poor. I have worked hard my whole life, used the money HaShem gave/gives me to take care of needs, responsibilities, and to help others. I have used my entire lifetime income in this matter, yet I still have more. HaShem has always provided my needs, and my few humble desires. He taught me from my youth how to manage money. I have run my life debt-free, and my life is enabled.
Despite never being rich, HaShem caused me to visit almost 30 countries on a humble income remaining debt-free throughout.
If you understand all money is for human need, and your person for service, you can, by HaShem's grace, go very far spiritually and accomplish much even if mostly known only to HaShem, if you understand you are obligated to Him, and this is His expectation of you, to do all you can to establish His righteousness upon this earth.
Work. Study. Love Him First by loving kindness and service to His Humanity.