Rashi: From this Terumah will be for the need of Hekdesh, for Har ha'Bayis ? 500 Kanim. The rest will be for Kohanim, like it says at the end of the Sefer (Perek 48). Radak ? Har ha'Bayis will be 500 by 500; 12,250 remain in the east, and similarly in the west. With the 500 of the Bayis, it was 25,000 in all. In the north, 4,750 remained, and similarly in the south. With the 500 of the Bayis, it was 10,000 in all. Malbim ? in addition, there were 50 Amos Migrash around the wall of Har ha'Bayis.