Step 1 :
Divide $ 3201 $ by $ 2020 $ and get the remainder

$$ 3201 : 2020 = 1 \text{ ( remainder is } \color{blue}{ 1181 } \text{ ) } $$

The remainder is positive ($ 1181 > 0 $), so we will continue with division.

Step 2 :
Divide $ 2020 $ by $ \color{blue}{ 1181 } $ and get the remainder

$$ 2020 : 1181 = 1 \text{ ( remainder is } \color{blue}{ 839 } \text{ ) } $$

The remainder is still positive ($ 839 > 0 $), so we will continue with division.

Step 3 :
Divide $ 1181 $ by $ \color{blue}{ 839 } $ and get the remainder

$$ 1181 : 839 = 1 \text{ ( remainder is } \color{blue}{ 342 } \text{ ) } $$

The remainder is still positive ($ 342 > 0 $), so we will continue with division.

Step 4 :
Divide $ 839 $ by $ \color{blue}{ 342 } $ and get the remainder

$$ 839 : 342 = 2 \text{ ( remainder is } \color{blue}{ 155 } \text{ ) } $$

The remainder is still positive ($ 155 > 0 $), so we will continue with division.

Step 5 :
Divide $ 342 $ by $ \color{blue}{ 155 } $ and get the remainder

$$ 342 : 155 = 2 \text{ ( remainder is } \color{blue}{ 32 } \text{ ) } $$

The remainder is still positive ($ 32 > 0 $), so we will continue with division.

Step 6 :
Divide $ 155 $ by $ \color{blue}{ 32 } $ and get the remainder

$$ 155 : 32 = 4 \text{ ( remainder is } \color{blue}{ 27 } \text{ ) } $$

The remainder is still positive ($ 27 > 0 $), so we will continue with division.

Step 7 :
Divide $ 32 $ by $ \color{blue}{ 27 } $ and get the remainder

$$ 32 : 27 = 1 \text{ ( remainder is } \color{blue}{ 5 } \text{ ) } $$

The remainder is still positive ($ 5 > 0 $), so we will continue with division.

Step 8 :
Divide $ 27 $ by $ \color{blue}{ 5 } $ and get the remainder

$$ 27 : 5 = 5 \text{ ( remainder is } \color{blue}{ 2 } \text{ ) } $$

The remainder is still positive ($ 2 > 0 $), so we will continue with division.

Step 9 :
Divide $ 5 $ by $ \color{blue}{ 2 } $ and get the remainder

$$ 5 : 2 = 2 \text{ ( remainder is } \color{blue}{ 1 } \text{ ) } $$

The remainder is still positive ($ 1 > 0 $), so we will continue with division.

Step 10 :
Divide $ 2 $ by $ \color{blue}{ 1 } $ and get the remainder

$$ 2 : \color{blue}{ \boxed { 1 }} = 2 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 1 }} $.

This solution can be visualized using a Venn diagram.

The GCD equals the product of the numbers at the intersection.

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