The GCF is 3.
What is the greatest common factor shared by 51 and 21?
3
24/3 = 8
21 divided in to 3 equal parts = 7
7
fractions which are equal to 21 = 21/1, 42/2, 63/3,...
1 x 21 3 x 7 7 x 3 21 x 1
You can do 7 times 3 and that will equal 21
3
there is no fraction between the numbers 3 21 and 421
21 is equal to 3 times 7.