Commentary for Exodus 26:22

ולירכתי AND FOR THE BACKPART — This is a term for “end”, as the Targum renders it, ולסיפי, “for the ends.” Because the entrance was on the east the east-side is called the front and the west-side the back. And this is why it is described here by a word denoting end, because the front is the head (the beginning) of a thing.

ולירכתי המשכן תעשה ששה קרשים. Seeing that each board was one and a half cubits wide, this would cover nine cubits in width. This left one half cubit at the north west corner and at the south west corner unaccounted for, seeing the width of the Tabernacle was ten cubits. The area left exposed would be taken up by the boards arranged in the east-westerly (long) sides of the Tabernacle, the last half cubit of each filling these two voids. This left the inside dimensions of the Tabernacle ten cubits wide with the problematic corners being enclosed in the manner we described. The view from the outside of the Tabernacle would show 90 degree corners without any indentations whatsoever.

תעשה ששה קרשים THOU SHALT MAKE SIX BOARDS — thus you have 9 cubits in the breadth.