Step 1 :
Divide $ 15490 $ by $ 10490 $ and get the remainder

$$ 15490 : 10490 = 1 \text{ ( remainder is } \color{blue}{ 5000 } \text{ ) } $$

The remainder is positive ($ 5000 > 0 $), so we will continue with division.

Step 2 :
Divide $ 10490 $ by $ \color{blue}{ 5000 } $ and get the remainder

$$ 10490 : 5000 = 2 \text{ ( remainder is } \color{blue}{ 490 } \text{ ) } $$

The remainder is still positive ($ 490 > 0 $), so we will continue with division.

Step 3 :
Divide $ 5000 $ by $ \color{blue}{ 490 } $ and get the remainder

$$ 5000 : 490 = 10 \text{ ( remainder is } \color{blue}{ 100 } \text{ ) } $$

The remainder is still positive ($ 100 > 0 $), so we will continue with division.

Step 4 :
Divide $ 490 $ by $ \color{blue}{ 100 } $ and get the remainder

$$ 490 : 100 = 4 \text{ ( remainder is } \color{blue}{ 90 } \text{ ) } $$

The remainder is still positive ($ 90 > 0 $), so we will continue with division.

Step 5 :
Divide $ 100 $ by $ \color{blue}{ 90 } $ and get the remainder

$$ 100 : 90 = 1 \text{ ( remainder is } \color{blue}{ 10 } \text{ ) } $$

The remainder is still positive ($ 10 > 0 $), so we will continue with division.

Step 6 :
Divide $ 90 $ by $ \color{blue}{ 10 } $ and get the remainder

$$ 90 : \color{blue}{ \boxed { 10 }} = 9 \text{ ( remainder is } \color{blue}{ 0 } \text{ ) } $$

The remainder is zero => GCD is the last divisor $ \color{blue}{ \boxed { 10 }} $.

This solution can be visualized using a Venn diagram.

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

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