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For a nonnegative integer $n$, the greatest common divisor of $n$ and $0$ is $n$ itself. This serves as the base case for the Euclidean algorithm, terminating the recursion when the second argument becomes zero.

Conditions: $n$ is a nonnegative integer.; The pair is $(n, 0)$.

For a nonnegative integer $n$, the greatest common divisor of $n$ and $0$ is $n$ itself. This serves as the base case for the Euclidean algorithm, terminating the recursion when the second argument becomes zero.

Conditions: $n$ is a nonnegative integer.; The pair is $(n, 0)$.