what is the lowest common denominator of 20 and 24

the lowest common denomenator is the smallest common factor of them so 20=1 times 2 times 2 times 524=1 times 2 times 2 times 2 times 3the lowest common denomenator is 1I think the question should have been. what is the greatest common factor (4) or what is the smallest common multiple (120)