The fraction will not repeat if we can make a reduced fraction with only some power of "2" in the denominator
So
1/12 = repeats
2/12 = 1/6 = repeats
3/12 = 1/4 = 1/2^2 = terminates
4/12 = 1/3 = repeats
5/12 = repeats
6/12 = 1/2 = terminates
7/12 = repeats
8/12 = 2/3 = repeats
9/12 = 3/4 = 3/2^2 = terminates
10/12 = 5/6 = repeats
11/12 = repeats