Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

"As for the breadth of the court on the west side, (there shall be) curtains fifty cubits; their pillars twenty; and the breadth of the court towards the front, on the east side, fifty cubits." The front is divided in Exo 27:14-16 into two כּתף, lit., shoulders, i.e., sides or side-pieces, each consisting of 15 cubits of hangings and three pillars with their sockets, and a doorway (שׁער), naturally in the middle, which was covered by a curtain (מסך) formed of the same material as the covering at the entrance to the dwelling, of 20 cubits in length, with four pillars and the same number of sockets. The pillars were therefore equidistant from one another, viz., 5 cubits apart. Their total number was 60 (not 56), which was the number required, at the distance mentioned, to surround a quadrangular space of 100 cubits long and 50 cubits broad. (Note: Although any one may easily convince himself of the correctness of these numbers by drawing a figure, Knobel has revived Philo's erroneous statement about 56 pillars and the double reckoning of the pillars in the corner. And the statement in Exo 27:14-16, that three pillars were to be made in front to carry the hangings on either side of the door, and four to carry the curtain which covered the entrance, may be easily shown to be correct, notwithstanding the fact that, as every drawing shows, four pillars would be required, and not three only, to carry 15 cubits of hangings, and five (not four) to carry a curtain 20 cubits broad, if the pillars were to be placed 5 cubits apart; for the corner pillars, as belonging to both sides, and the pillars which stood between the hangings and the curtain on either side, could only be reckoned as halves in connection with each side or each post; and in reckoning the number of pillars according to the method adopted in every other case, the pillar from which you start would not be reckoned at all. Now, if you count the pillars of the eastern side upon this principle (starting from a corner pillar, which is not reckoned, because it is the starting-point and is the last pillar of the side wall), you have 1, 2, 3, then 1, 2, 3, 4, and then again 1, 2, 3; that is to say, 3 pillars for each wing and 4 for the curtain, although the hangings of each wing would really be supported by 4 pillars, and the curtain in the middle by 5.)