In parshas Terumah (Shemos 27:1) the Jewish people received instructions to builid the alter. The width of the Courtyard of the Mishkan (Tabernacle) is 50 amos [see “A”] (Shemos 27:12). The width of the Mishkan is 10 amos [see “B”](Rashi on Shemos 26:23). The space between the sides of the Mishkan and the sides of the courtyard is the same on each side [see “C”]. The Mishkan was exactly in the middle of the courtyard. (Rashi on Shemos 27:18) How much is the space between the side of the Mishkan and the side of the courtyard?
(50 – 10) / 2 = 20 amos
Click the picture below to get an image to copy or print.