5.
“And Noah was five hundred years old; and Noah begat Shem” (v, 32).
“And Noah was six hundred years old when the flood of waters was upon the earth” (vii, 6).
“Shem was a hundred years old, and he begat Arphaxad two years after the flood” (xi, 10).
If Noah was five hundred years old when he begat Shem, and six hundred years old at the time of the Flood, Shem was one hundred years old at the time of the Flood. If Shem begat Arphaxad two years after the Flood, he was one hundred and two years old when he begat Arphaxad.