GCD from Prime Decomposition/Examples/169 and 273

Example of Use of GCD from Prime Decomposition

The greatest common divisor of $169$ and $273$ is:

$\gcd \set {169, 273} = 13$


Proof

\(\ds 169\) \(=\) \(\ds 13^2\)
\(\ds 273\) \(=\) \(\ds 3 \times 7 \times 13\)
\(\ds \leadsto \ \ \) \(\ds 169\) \(=\) \(\ds 3^0 \times 7^0 \times 13^2\)
\(\ds 273\) \(=\) \(\ds 3^1 \times 7^1 \times 13^1\)
\(\ds \leadsto \ \ \) \(\ds \gcd \set {169, 273}\) \(=\) \(\ds 3^0 \times 7^0 \times 13^1\)
\(\ds \) \(=\) \(\ds 13\)

$\blacksquare$


Sources

  • 1971: George E. Andrews: Number Theory ... (previous) ... (next): $\text {2-4}$ The Fundamental Theorem of Arithmetic: Exercise $6 \ \text{(b)}$