Step 1 :
Divide $ 1860 $ by $ 484 $ and get the remainder

$$ 1860 : 484 = 3 \text{ ( remainder is } \color{blue}{ 408 } \text{ ) } $$

The remainder is positive ($ 408 > 0 $), so we will continue with division.

Step 2 :
Divide $ 484 $ by $ \color{blue}{ 408 } $ and get the remainder

$$ 484 : 408 = 1 \text{ ( remainder is } \color{blue}{ 76 } \text{ ) } $$

The remainder is still positive ($ 76 > 0 $), so we will continue with division.

Step 3 :
Divide $ 408 $ by $ \color{blue}{ 76 } $ and get the remainder

$$ 408 : 76 = 5 \text{ ( remainder is } \color{blue}{ 28 } \text{ ) } $$

The remainder is still positive ($ 28 > 0 $), so we will continue with division.

Step 4 :
Divide $ 76 $ by $ \color{blue}{ 28 } $ and get the remainder

$$ 76 : 28 = 2 \text{ ( remainder is } \color{blue}{ 20 } \text{ ) } $$

The remainder is still positive ($ 20 > 0 $), so we will continue with division.

Step 5 :
Divide $ 28 $ by $ \color{blue}{ 20 } $ and get the remainder

$$ 28 : 20 = 1 \text{ ( remainder is } \color{blue}{ 8 } \text{ ) } $$

The remainder is still positive ($ 8 > 0 $), so we will continue with division.

Step 6 :
Divide $ 20 $ by $ \color{blue}{ 8 } $ and get the remainder

$$ 20 : 8 = 2 \text{ ( remainder is } \color{blue}{ 4 } \text{ ) } $$

The remainder is still positive ($ 4 > 0 $), so we will continue with division.

Step 7 :
Divide $ 8 $ by $ \color{blue}{ 4 } $ and get the remainder

$$ 8 : \color{blue}{ \boxed { 4 }} = 2 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 4 }} $.

This solution can be visualized using a Venn diagram.

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

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