The GCD of given numbers is 129.
Step 1 :
Divide $ 387 $ by $ 129 $ and get the remainder
The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 129 }} $.
We can summarize an algorithm into a following table.
387 | : | 129 | = | 3 | remainder ( 0 ) |
GCD = 129 |
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.