[QUOTE][b]Hey, did you know if you convert the number of years the long-lived patriarchs survived to months that it turns out to be within natural human lifespans (75 years of age)?[/QUOTE]
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Remember Abraham's wife Sarah, who was 90 years old when she had a son? We were told that Sarah had grown old and out of the "ways of women" before reaching 90. If we divide 90 by twelve as you suggest we have Sarah reaching menopause before age seven and a half.
We are told that Sarah is old at 90, but still attractive enough at that age to get the attention of Abimelech. (Abraham told him she was his sister rather than his wife so he wouldn't murder him for her; by the way, he was eight years old by your reckoning when he was told to expect a son within the year's end) and Sarah lived on to the ripe old age of 127, or about 11 by your reckoning, after having finally given birth to a son. Abraham died at the ripe old age ("full of years") of 175, or nearly 15 by your reckoning. By then his son Isaac was already seeking a wife (born to Abraham when he was 9), meaning Isaac was courting Rebekah at age 6.
Enough of that family history, let's look at another convenient example from Genesis. Shem was five hundred years old (42 by your reckoning) when his son Arpachshad was born two years after the Flood. So far, so good. But Arpachshad had a child at 35 years of age according to the Bible, that is, when he was almost three years old according to your interpretation.