The GCD of given numbers is 3.
factors of 6 are : | 1 , 2 , 3 , 6 |
factors of 9 are : | 1 , 3 , 9 |
factors of 12 are : | 1 , 2 , 3 , 4 , 6 , 12 |
factors of 15 are : | 1 , 3 , 5 , 15 |
factors of 18 are : | 1 , 2 , 3 , 6 , 9 , 18 |
We see that the Greatest Common Factor = 3.