Step 1 :
Divide $ 756 $ by $ 528 $ and get the remainder

$$ 756 : 528 = 1 \text{ ( remainder is } \color{blue}{ 228 } \text{ ) } $$

The remainder is positive ($ 228 > 0 $), so we will continue with division.

Step 2 :
Divide $ 528 $ by $ \color{blue}{ 228 } $ and get the remainder

$$ 528 : 228 = 2 \text{ ( remainder is } \color{blue}{ 72 } \text{ ) } $$

The remainder is still positive ($ 72 > 0 $), so we will continue with division.

Step 3 :
Divide $ 228 $ by $ \color{blue}{ 72 } $ and get the remainder

$$ 228 : 72 = 3 \text{ ( remainder is } \color{blue}{ 12 } \text{ ) } $$

The remainder is still positive ($ 12 > 0 $), so we will continue with division.

Step 4 :
Divide $ 72 $ by $ \color{blue}{ 12 } $ and get the remainder

$$ 72 : \color{blue}{ \boxed { 12 }} = 6 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 12 }} $.

This solution can be visualized using a Venn diagram.

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

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