Charles Ellicott Commentary Exodus 27:11-12

"And likewise for the north side in length there shall be hangings a hundred cubits long, and the pillars thereof twenty, and their sockets twenty, of brass; the hooks of the pillars, and their fillets, of silver. And for the breadth of the court on the west side shall be hangings of fifty cubits; their pillars ten, and their sockets ten." — Exodus 27:11-12 (ASV)

The north side ... This side of the court was to be in exact correspondence with the south. The western side was to be of only half the length (fifty cubits), and required therefore only half the number of pillars and sockets.