THE SOLUTION:
9 or 10.
The numbers represent the classic scoring system in the game of chess. Pawns are worth 1 point, Bishops and Knights (always marked as N instead of K to avoid confusion with the King) are worth 3 points each, and Rooks are worth 5 points. The Queen, the most valuable piece, is worth 9 points when discounting pawns, or 10 points when including them.