וְאֵ֖לֶּה בְּנֵ֣י שׁוּתָ֑לַח לְעֵרָ֕ן מִשְׁפַּ֖חַת הָעֵרָנִֽי׃
Et ceux-ci sont les descendants de Choutélah: Erân, d’où la famille des Eranites.
Rabbeinu Bahya
I will now give you an explanation of a general nature:
Remember that the Tabernacle was 30 cubits long and 10 cubits wide. Its height was also 10 cubits. We know that it was 30 cubits long as in connection with the upright beams, קרשים, which formed the walls, the Torah wrote that 20 such beams be constructed for the wall for the south side (verse 18). Each beam was 11/2 cubits wide (verse 16) and its height was 10 cubits (verse 16). There were 20 such beams for the north wall and 20 for the south wall. The combined width of these 20 beams was 30 cubits, giving the Tabernacle an overall length of 30 cubits. We know that the Tabernacle’s width was 10 cubits as the Torah writes (verse 22) that for the back of the Tabernacle 6 beams were to be constructed. Add to this the fact that the Torah describes the western wall as comprising 8 beams (verse 25), plus the fact that two beams had been constructed to form the corners (verse 23) and you know that the two corner beams were positioned so that their width was facing west whereas their thickness was facing north and south respectively making the outside width of the Tabernacle 12 cubits. In other words, the inside measurement of the Tabernacle was 30 by 10, whereas the outside measurement was 31 by 12 cubits.
Onkelos translates the word ולירכתי, in verse 22 as ולסיפי, “and for the end of.” The reason he does so is that the western wall is the “end” of a process which began in the east, with the pillars and the curtain at the entrance to the Tabernacle. There were no beams at the eastern end of the Tabernacle. The five pillars which supported the מסך, “screening curtain,” formed the entrance to the Tabernacle on the eastern side (compare verse 36).
Remember that the Tabernacle was 30 cubits long and 10 cubits wide. Its height was also 10 cubits. We know that it was 30 cubits long as in connection with the upright beams, קרשים, which formed the walls, the Torah wrote that 20 such beams be constructed for the wall for the south side (verse 18). Each beam was 11/2 cubits wide (verse 16) and its height was 10 cubits (verse 16). There were 20 such beams for the north wall and 20 for the south wall. The combined width of these 20 beams was 30 cubits, giving the Tabernacle an overall length of 30 cubits. We know that the Tabernacle’s width was 10 cubits as the Torah writes (verse 22) that for the back of the Tabernacle 6 beams were to be constructed. Add to this the fact that the Torah describes the western wall as comprising 8 beams (verse 25), plus the fact that two beams had been constructed to form the corners (verse 23) and you know that the two corner beams were positioned so that their width was facing west whereas their thickness was facing north and south respectively making the outside width of the Tabernacle 12 cubits. In other words, the inside measurement of the Tabernacle was 30 by 10, whereas the outside measurement was 31 by 12 cubits.
Onkelos translates the word ולירכתי, in verse 22 as ולסיפי, “and for the end of.” The reason he does so is that the western wall is the “end” of a process which began in the east, with the pillars and the curtain at the entrance to the Tabernacle. There were no beams at the eastern end of the Tabernacle. The five pillars which supported the מסך, “screening curtain,” formed the entrance to the Tabernacle on the eastern side (compare verse 36).
Or HaChaim
Baba Batra 121 raises the point that the scholars were not certain whether the land was distributed in accordance with the number of tribes or in accordance with the number of individual people. They tried to answer this by reference to the verse in our portion where the Torah said "be they numerous or few" meaning that it was not divided in accordance with the number of individuals over the age of twenty (verse 36). They quoted a Baraitha according to which the land of Israel will be divided up amongst 13 tribes in messianic times, whereas in Joshua's time it was divided amongst 12 tribes. Thus far the Talmud there. The Talmud apparently was unaware of the Baraitha we mentioned in the Sifri, where this point is derived from the words איש לפי פקודיו. It is reasonable to assume that the scholar in the Talmud who said that in the future the land of Israel would be shared out between thirteen tribes also based his opinion on these words.