1 is 12.
2 is 4.
3 is 7.
4 I think is 4.
5 I have no idea what it is.
6 is 5.
7 is 25,30 5,10 and 15,35.
8 is 12.
9 is 7.
10 is 8.
11 is A.
12 is that you write down all of the factors that make up to that number and look at the numbers and see which one is the same on each side and see which one is the greatest in this case the GCF is 6