Given that the combined width of the curtains, which were spread along the length of the Mishkan, was forty Amos), how much of the western (outer) wall remained uncovered?
Rashi #1 (in Pasuk 5, citing Shabbos, 98b): Thirty Amos covered the inside of the Mishkan plus the pillars on the east, 1 one Amah covered the Kerashim in the west, and nine Amos, the western wall - leaving two Amos, including the socket, uncovered.
Rashi #2 (in Pasuk 5, citing the Beraisa of 49 Midos): Thirty Amos covered the inside of the Mishkan, one Amah, the pillars that held the Masach in front of the Mishkan; one Amah covered the Kerashim in the west, and eight Amos, the western wall - leaving the sockets and one Amah of the wall uncovered. From a different perspective, Rashi and the Rashbam later, in Pasuk 32, explain that the two twenty-Amah curtains were joined by the hooks in the middle. Seeing as the Paroches was directly underneath the hooks, it transpires that the twenty Amos covered the Kodesh and twenty, the Kodesh Kodashim, including the Amah thickness of the west-wall, leaving nine Amos to hang down the back of the Kodesh Kodshim. 2
Rashbam (in Pasuk 9): The curtains covered the thirty Amos of the Mishkan, and all ten Amos 3 of the western wall.
Rashi: This is difficult, since Pasuk 33 states that the Paroches was under the golden hooks that joined the two sets of curtains. According to this Beraisa, the hooks were nineteen Amos east of the Masach, and the Paroches was one Amah west of this! Riva: The Beraisa holds that the pillars of the Paroches were twenty Amos into the Mishkan, and the Paroches was hung to their east, and likewise, the screen hung from the east side of its pillars, to complete the twenty Amos of the Kodesh (outside the Kodesh ha'Kodoshim). (If so, one Amah of the Kodesh was within the curtains, but outside the boards! And the Kodesh ha'Kodashim was eleven Amos long! This requires investigation. - PF)
