Find Greatest Common Divisor of 18 and 7, using Euclidean algorithm.
Answer
The GCD of given numbers is 1.
Explanation
Step 1 :
Divide $ 18 $ by $ 7 $ and get the remainder
The remainder is positive ($ 4 > 0 $), so we will continue with division.
Step 2 :
Divide $ 7 $ by $ \color{blue}{ 4 } $ and get the remainder
The remainder is still positive ($ 3 > 0 $), so we will continue with division.
Step 3 :
Divide $ 4 $ by $ \color{blue}{ 3 } $ and get the remainder
The remainder is still positive ($ 1 > 0 $), so we will continue with division.
Step 4 :
Divide $ 3 $ 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.
| 18 | : | 7 | = | 2 | remainder ( 4 ) | ||||||
| 7 | : | 4 | = | 1 | remainder ( 3 ) | ||||||
| 4 | : | 3 | = | 1 | remainder ( 1 ) | ||||||
| 3 | : | 1 | = | 3 | remainder ( 0 ) | ||||||
| GCD = 1 | |||||||||||
This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.