Although there are a number of ambiguities in the chronological system that runs through the Masoretic text, these numbers are generally quite easy to come up with from a literal reading of Genesis 5, 11 and 25; Exodus 12:40; 1 Kings 6:1; the Exile and Return as described in 2 Kings 25 and Ezra; and passages chronicling the reigns of the kings of Judah. The writings of Josephus and the Septuagint give very different numbers throughout.