Numbers 1 - 4

The Lord commanded Moses and Aaron -

"Take ye the sum of all the congregation of the children of Israel, after their families, by the house of their fathers, with the number of their names, every male by their polls;
3 From twenty years old and upward, all that are able to go forth to war in Israel..." (Old Testament Numbers 1:2 - 3)

It becomes clear that it was important to the Lord that his people are numbered. Moroni tells us of his people that -

"...after they had been received unto baptism, and were wrought upon and cleansed by the power of the Holy Ghost, they were numbered among the people of the church of Christ..." (Book of Mormon Moroni 6:4)

But what I think is important is that in addition to the new members being numbered -

"...their names were taken, that they might be remembered and nourished by the good word of God, to keep them in the right way, to keep them continually watchful unto prayer, relying alone upon the merits of Christ, who was the author and the finisher of their faith." (Book of Mormon Moroni 6:4)

In what we have in the Book of Numbers, it does not necessarily say their names were taken. As much as we are concerned with numbers, more important is that each number has a name and the Lord loves them individually.
I think their is another item of significance in these verses has to do with numbering the firstborn of Israel. As the -

"....LORD said unto Moses, Number all the firstborn of the males of the children of Israel from a month old and upward, and take the number of their names.
41 And thou shalt take the Levites for me (I am the LORD) instead of all the firstborn among the children of Israel..." (Old Testament Numbers 3:40 - 41)

"...Because all the firstborn are mine; for on the day that I smote all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel..." (Old Testament Numbers 3:13)

It seems to me that because the firstborn were in a sense symbolically saved by the blood of a lamb, they are the Lord's, and should be dedicated to his service.

"For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's..." (New Testament 1 Corinthians 6:20)

Therefore, Moroni tells us -

"...none were received unto baptism save they took upon them the name of Christ, having a determination to serve him to the end." (Book of Mormon Moroni 6:3)

And same being taught in the modern Church -

"All those who humble themselves before God, and desire to be baptized, and come forth with broken hearts and contrite spirits, and witness before the church that they have truly repented of all their sins, and are willing to take upon them the name of Jesus Christ, having a determination to serve him to the end..." (Doctrine and Covenants Section 20:37)

"Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood." (New Testament Acts 20:28)