Step 1 :
Divide $ 504 $ by $ 295 $ and get the remainder

$$ 504 : 295 = 1 \text{ ( remainder is } \color{blue}{ 209 } \text{ ) } $$

The remainder is positive ($ 209 > 0 $), so we will continue with division.

Step 2 :
Divide $ 295 $ by $ \color{blue}{ 209 } $ and get the remainder

$$ 295 : 209 = 1 \text{ ( remainder is } \color{blue}{ 86 } \text{ ) } $$

The remainder is still positive ($ 86 > 0 $), so we will continue with division.

Step 3 :
Divide $ 209 $ by $ \color{blue}{ 86 } $ and get the remainder

$$ 209 : 86 = 2 \text{ ( remainder is } \color{blue}{ 37 } \text{ ) } $$

The remainder is still positive ($ 37 > 0 $), so we will continue with division.

Step 4 :
Divide $ 86 $ by $ \color{blue}{ 37 } $ and get the remainder

$$ 86 : 37 = 2 \text{ ( remainder is } \color{blue}{ 12 } \text{ ) } $$

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

Step 5 :
Divide $ 37 $ by $ \color{blue}{ 12 } $ and get the remainder

$$ 37 : 12 = 3 \text{ ( remainder is } \color{blue}{ 1 } \text{ ) } $$

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

Step 6 :
Divide $ 12 $ by $ \color{blue}{ 1 } $ and get the remainder

$$ 12 : \color{blue}{ \boxed { 1 }} = 12 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

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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