בראשית, פרק ה׳, פסוק י״ג

The genealogical records of early humanity document remarkably long lifespans, carefully tracking the years lived both before and after the birth of the next generation. Following the birth of his son Mahalalel, Kenan lived an additional eight hundred and forty years, during which he fathered more sons and daughters.

The specific method used to count these years reveals an underlying numerical structure. The total is built upon a foundational base of eight hundred years. The remaining forty years are then formed by adding accumulated months to this base, specifically broken down into a calculation of one hundred and twenty months alongside another three hundred and sixty months [קאסוטו].