At first it seems clear that Noah was 500 years older than Shem.
Gen 5:32 And Noah was five hundred years old: and Noah begat Shem, Ham, and Japheth. (KJV)
However, if we calculate from a different perspective, it seems Noah may have been as much as 502 years older than Shem.
Noah’s age at the time of the flood:
Gen 9:28-29 And Noah lived after the flood three hundred and fifty years. And all the days of Noah were nine hundred and fifty years: and he died*** (KJV)
With those verses it seems Noah was 600 years old at the time of the flood (950 -350).
Shem’s age at the time of the flood:
Gen 11:10 These are the generations of Shem: Shem was an hundred years old, and begat Arphaxad two years after the flood: (KJV)
Per that verse it seems Shem was 98 years old at the time of the flood (i.e. 100 – 2).
Combining the last 3 verses, Noah was 502 years older than Shem (i.e. Noah 600 years old at the time of the flood less Shem at 98).
Was Noah only 500 years older than Shem or as much as 502 years older? How can the 2 year difference be reconciled?