Here is what The Watchtower expects the reader to retain after reading the October 1st article.
THE WATCHTOWER, DECEMBER 15, 2011, page 31
Do You Remember?
* How do we know when ancient Jerusalem fell to the Babylonians?
Classical historians give mixed, conflicting details about the Babylonian kings and their reigns. Yet, scholars agree that Cyrus II conqured Babylon in 539 B.C.E., a pivotal date. The Jews were released, and they arrived in their homeland by 537 B.C.E. The Bible says that their exile was 70 years long. So Jerusalem must have fallen in 607 B.C.E. (2 Chron. 36:21,22; Jer. 29:10; Dan. 9:1,2)-10/1, pages 26-31.