The GCD of given numbers is 1.
| factors of 13 are : | 1 , 13 |
| factors of 369 are : | 1 , 3 , 9 , 41 , 123 , 369 |
We see that the Greatest Common Factor = 1.
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.