DID YOU KNOW?
The answer
Eighteen. The note closes Psalm 72, and the book keeps going for seventy-eight more psalms, eighteen of them headed "Of David." The note belonged to one earlier collection. The Psalms are a collection of smaller collections, gathered from different times and places.
Why it’s interesting
The line saying David's prayers are over closes a psalm headed "Of Solomon": his son's psalm, not his.
Scholarly consensus
Learn the Bible.
Not just the stories, but the history, authorship, and scholarship behind it.