In Halachic literature, Sefer BeMidbar is frequently called Chumash HaPekudim, the Chumash of Counting, or more precisely, the Chumash of Enumeration. This is because in addition to the two major censuses of Bnai Yisrael, described at the beginning and the end of the Sefer, we find other "countings" there, including counts of the Leviyim, the numbers and types of Korbanos brought during the dedication of the Mishkan, the order of camping and of travel in the desert, the list of Meraglim (spies), the numbers and types of Korbanos brought daily and on Shabbos and holidays, the enumeration of the borders of Eretz Yisrael, and finally, the itinerary of the Jews during their forty-year stay in Midbar Sinai. This counting theme is introduced at the very beginning, in the opening Pesukim of Parshas Bemidbar.
Thirty days after the Mishkan was put into use, Hashem commanded Moshe and Aharon to make a very detailed count of Bnai Yisrael. The Ramban describes the procedure in detail, (במדבר א':כ', בד"ה ויתילדו): Every eligible person (which excludes the ערב רב, the hangers-on) appears at the door of the Ohel Moed, half-Shekel in hand, and tells Moshe and the Nesi'im his name, parents' names, family name, and Sheivet (tribe). He then deposits his half-Shekel in the container of the appropriate Sheivet. According to some (the Malbim, for example), he actually writes his name on a list, and the names are subsequently counted.
The Malbim understands the words "במספר שמות...לגלגלתם" ("according to the count of their names...by a head count"), found several times in the Parsha, as a directive to count Bnai Yisrael twice -- once via their names, whereby each individual is recognized, and again anonymously, through the half-Shekels. There is a dichotomy of purpose in this census. On one hand, the individual is emphasized to an unprecedented (and not repeated) extent. Not only his name, but his entire lineage is recorded, just as if he were in the highest echelons of the community. On the other hand, each person is also represented by a uniform, anonymous half-Shekel. The identity of the individual is thus submerged within the community as a whole.
We can begin to resolve this paradox by realizing just when this census took place. It was a unique time in Jewish history. The חטא העגל, the sin of the Golden Calf, had passed. Those persons seriously involved did not survive the aftermath of that episode, while the survivors had been forgiven by Hashem. The Mishkan was set up and was in daily use; the Shechinah dwelled in the midst of the people. This Jewish nation was ready to enter Eretz Yisrael. This was a united community -- in the words of the Midrash, בלב אחד כאיש אחד, with a single heart, as one people.
Even so, Hashem emphasized the counting of individuals -- reminding us that it is the individual contributions that make up the whole, and that if there is a problem with a single individual, the entire community is affected.
The Chidushei HaRim put it this way: The reason Hashem counted us is to show that we are a דבר שבמנין -- a collection where each individual is important, where we are counted, one by one. The Halacha is that דבר שבמנין, אפילו באלף לא בטל -- something important enough so that its elements are counted out one by one, rather than being measured out in bulk, never loses its individuality, and can never disappear into the overall background.This applies to the individuals within the community as well as to Bnai Yisrael as a whole, who will never disappear, no matter how small a minority among the nations of the world.
Over ninety percent of the time (at least outside of Eretz Yisrael), Parshas BeMidbar is read on the Shabbos before Shavuos. Is there a significance to this? The Kotzker Rebbe commented on the reason why Shavuos is called זמן מתן תורתנו, the time when the Torah was given to us, instead of זמן קבלת תורתנו, the time we accepted the Torah (which is stressed, for example, in the first Mishnah in Pirkei Avos that says משה קבל תורה מסיני, emphasizing the acceptance of Torah). He pointed out that the Torah was given to Bnai Yisrael as a nation, but the Torah can be accepted only by individuals. We received the Torah on the sixth of Sivan בלב אחד כאיש אחד, but no matter how unified we were, acceptance of the Torah is a decision and an experience that is unique to each individual. Also, there can be no fixed date for קבלת התורה, because every time we learn Torah we accept it once again.
Shavuos, then, is a very appropriate time to renew our acceptance of Torah, and to turn this renewal into a continuing process, by setting aside part of every single day for learning Torah.