Step 1 :
Divide $ 625 $ by $ 512 $ and get the remainder

$$ 625 : 512 = 1 \text{ ( remainder is } \color{blue}{ 113 } \text{ ) } $$

The remainder is positive ($ 113 > 0 $), so we will continue with division.

Step 2 :
Divide $ 512 $ by $ \color{blue}{ 113 } $ and get the remainder

$$ 512 : 113 = 4 \text{ ( remainder is } \color{blue}{ 60 } \text{ ) } $$

The remainder is still positive ($ 60 > 0 $), so we will continue with division.

Step 3 :
Divide $ 113 $ by $ \color{blue}{ 60 } $ and get the remainder

$$ 113 : 60 = 1 \text{ ( remainder is } \color{blue}{ 53 } \text{ ) } $$

The remainder is still positive ($ 53 > 0 $), so we will continue with division.

Step 4 :
Divide $ 60 $ by $ \color{blue}{ 53 } $ and get the remainder

$$ 60 : 53 = 1 \text{ ( remainder is } \color{blue}{ 7 } \text{ ) } $$

The remainder is still positive ($ 7 > 0 $), so we will continue with division.

Step 5 :
Divide $ 53 $ by $ \color{blue}{ 7 } $ and get the remainder

$$ 53 : 7 = 7 \text{ ( remainder is } \color{blue}{ 4 } \text{ ) } $$

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

Step 6 :
Divide $ 7 $ by $ \color{blue}{ 4 } $ and get the remainder

$$ 7 : 4 = 1 \text{ ( remainder is } \color{blue}{ 3 } \text{ ) } $$

The remainder is still positive ($ 3 > 0 $), so we will continue with division.

Step 7 :
Divide $ 4 $ by $ \color{blue}{ 3 } $ and get the remainder

$$ 4 : 3 = 1 \text{ ( remainder is } \color{blue}{ 1 } \text{ ) } $$

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

Step 8 :
Divide $ 3 $ by $ \color{blue}{ 1 } $ and get the remainder

$$ 3 : \color{blue}{ \boxed { 1 }} = 3 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

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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