The GCD of given numbers is 1.
Step 1 :
Divide $ 13 $ by $ 8 $ and get the remainder
The remainder is positive ($ 5 > 0 $), so we will continue with division.
Step 2 :
Divide $ 8 $ by $ \color{blue}{ 5 } $ and get the remainder
The remainder is still positive ($ 3 > 0 $), so we will continue with division.
Step 3 :
Divide $ 5 $ by $ \color{blue}{ 3 } $ and get the remainder
The remainder is still positive ($ 2 > 0 $), so we will continue with division.
Step 4 :
Divide $ 3 $ by $ \color{blue}{ 2 } $ and get the remainder
The remainder is still positive ($ 1 > 0 $), so we will continue with division.
Step 5 :
Divide $ 2 $ by $ \color{blue}{ 1 } $ and get the remainder
The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 1 }} $.
We can summarize an algorithm into a following table.
13 | : | 8 | = | 1 | remainder ( 5 ) | ||||||||
8 | : | 5 | = | 1 | remainder ( 3 ) | ||||||||
5 | : | 3 | = | 1 | remainder ( 2 ) | ||||||||
3 | : | 2 | = | 1 | remainder ( 1 ) | ||||||||
2 | : | 1 | = | 2 | remainder ( 0 ) | ||||||||
GCD = 1 |
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.