בראשית, פרק י״א, פסוק ט״ו

The chronological record of Shem's descendants reveals a highly consistent and continuous numerical structure. Following the birth of his son Eber, Shelah lived for another 403 years. This specific duration perfectly mirrors the remaining years lived by his father, Arpachshad, after Shelah himself was born [קאסוטו]. When combining these years with the time he lived prior to his son's birth, Shelah reached a total age of 433 years.

The numerical makeup of this lifespan follows a distinct pattern found throughout this family line. It consists of a base of 400 years, with an addition of 33 years. These extra 33 years equal exactly 396 months, which breaks down into 360 months plus another 36 months. This specific mathematical formula repeats itself across the age calculations of the entire genealogy, highlighting a deliberate order in the historical timeline.