The GCD of given numbers is 20.
Step 1 :
Divide $ 400 $ by $ 60 $ and get the remainder
The remainder is positive ($ 40 > 0 $), so we will continue with division.
Step 2 :
Divide $ 60 $ by $ \color{blue}{ 40 } $ and get the remainder
The remainder is still positive ($ 20 > 0 $), so we will continue with division.
Step 3 :
Divide $ 40 $ by $ \color{blue}{ 20 } $ and get the remainder
The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 20 }} $.
We can summarize an algorithm into a following table.
400 | : | 60 | = | 6 | remainder ( 40 ) | ||||
60 | : | 40 | = | 1 | remainder ( 20 ) | ||||
40 | : | 20 | = | 2 | remainder ( 0 ) | ||||
GCD = 20 |
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.