least common denominator for both numbers is 9, so divide both numbers by 9, you get 2:1 ratio least common denominator is calculated by dividing both numbers by the same number until you can't divide anymore by the same number, (try dividing it by 2 or 3, it usually works- if you divide this by 3 you get 6:3, which can then be further divided by 3 again to get 2:1) then, you can take that ratio, and multiply it by whatever you want, even fractions 4:2 6:3 8:4 or 3:1.5 7:3.5