9, 3, 2, 1 = ?? - Find which number replace question mark? - Genius Math Puzzles - 9, 3, 2, 1 = ?? – Find which number replace question mark? – Geni... i0.wp.com/picsdownloadz.com/wp-content/uploads/2016/09/9312-Math-Puzzles-Only-for-genius.jpg?fit=700%2C500