Arphaxad

Genesis 5:32 says that Noah was 500 when he begat Shem, Ham, and Japheth. Genesis 7:11 says that the Flood started in Noah’s 600th year. Genesis 8:13 says the Flood waters completely receded in Noah’s 601st year (around 10 and a half months after it started). And Genesis 11:10 says that Shem begat Arphaxad two years after the Flood when he was 100 years old. Now, the math doesn’t add up because if the Flood ended in Noah’s 601st year, Shem should have been 103 (or 102 if the beginning of the Flood is counted though that’s unlikely).