The GCD of given numbers is 7.
Step 1 :
Divide $ 91 $ by $ 63 $ and get the remainder
The remainder is positive ($ 28 > 0 $), so we will continue with division.
Step 2 :
Divide $ 63 $ by $ \color{blue}{ 28 } $ and get the remainder
The remainder is still positive ($ 7 > 0 $), so we will continue with division.
Step 3 :
Divide $ 28 $ by $ \color{blue}{ 7 } $ and get the remainder
The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 7 }} $.
We can summarize an algorithm into a following table.
91 | : | 63 | = | 1 | remainder ( 28 ) | ||||
63 | : | 28 | = | 2 | remainder ( 7 ) | ||||
28 | : | 7 | = | 4 | remainder ( 0 ) | ||||
GCD = 7 |
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.