What is "Kol ha'Terumah"?
Rashi: It is the 25,000 Kanim by 25,000 separated from the big Terumah (the width of 25,000 from the eastern border to the western border).
What is the meaning of "Revi'is"?
Rashi: It is square.
Malbim: The Terumah for Achuzas ha'Ir was a quarter of what remained from the strip. The city was 5,000, and the remainder was 20,000 1 .
This refers to length or width. The area of the city was 25 million square Kanim, one part in 24 of the remaining area (600 million square Kanim. ? PF)
Why does it say "El Achuzas ha'Ir"?
Rashi: This is like v'El Achuzas ha'Ir. The area is for Kohanim, Leviyim, and the district of the city.
Radak: This is like Im Achuzas ha'Ir; the city is amidst the calculation of 25,000.
