First let's make a factor list of each of these numbers:
16 = 1, 2, 4, 8, 16
1 * 16 = 16
2 * 8 = 16
4 * 4 = 16
18 = 1, 2, 3, 6, 9, 18
1 * 18 = 18
2 * 9 = 18
3 * 6 = 18
30 = 1, 2, 3, 5, 6, 10, 15, 30
1 * 30 = 30
2 * 15 = 30
3 * 10 = 30
5 * 6 = 30
What factors do all these numbers have in common?
16 = 1, 2, 4, 8, 16
18 = 1, 2, 3, 6, 9, 18
30 = 1, 2, 3, 5, 6, 10, 15, 30
All three numbers have the factors 1 and 2 in common.
The greatest common factor is 2. This is because 2 is the largest factor all three numbers have in common
Hope this helped!
~Just a girl in love with Shawn Mendes