GCD from Prime Decomposition/Examples/2187 and 999

Example of Use of GCD from Prime Decomposition

The greatest common divisor of $2187$ and $999$ is:

$\gcd \set {2187, 999} = 27$


Proof

\(\ds 2187\) \(=\) \(\ds 3^7\)
\(\ds 999\) \(=\) \(\ds 3^3 \times 37\)
\(\ds \leadsto \ \ \) \(\ds 2187\) \(=\) \(\ds 3^7 \times 37^0\)
\(\ds 999\) \(=\) \(\ds 3^3 \times 37^1\)
\(\ds \leadsto \ \ \) \(\ds \gcd \set {2187, 999}\) \(=\) \(\ds 3^3 \times 37^0\)
\(\ds \) \(=\) \(\ds 27\)

$\blacksquare$


Sources

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