John Gill Commentary Genesis 5:10

"and Enosh lived after he begat Kenan eight hundred and fifteen years, and begat sons and daughters:" — Genesis 5:10 (ASV)

And Enos lived, after he begat Cainan, eight hundred and fifteen years The Septuagint version is seven hundred and fifteen; the hundred which is wanting is to be supplied from the preceding verse, which in that version has an hundred too much: and begat sons and daughters ; others besides Enos, as very likely he had before he was born.