Lucky Guess or Mathmatical Genius?

This morning as Dexter was helping clean up by putting his crayons back in their bucket, Dexter was picking up handfuls and insisting each handful was "three" crayons. I would correct him with the accurate number but he was having none of it. Eventually I tired of simply providing the correct quantity and began to get a little creative. When I responded to, "It's three, Mommy," with, "Well, that's three plus four," Dexter replied, "Equals seven." What?!