The GCD of given numbers is 168.
Step 1 :
Divide $ 504 $ by $ 168 $ and get the remainder
The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 168 }} $.
We can summarize an algorithm into a following table.
| 504 | : | 168 | = | 3 | remainder ( 0 ) |
| GCD = 168 | |||||
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.