GCD from Prime Decomposition/Examples/64 and 81

Example of Use of GCD from Prime Decomposition

The greatest common divisor of $64$ and $81$ is:

$\gcd \set {64, 81} = 1$


Proof

\(\ds 64\) \(=\) \(\ds 2^6\)
\(\ds 81\) \(=\) \(\ds 3^4\)
\(\ds \leadsto \ \ \) \(\ds 64\) \(=\) \(\ds 2^6 \times 3^0\)
\(\ds 81\) \(=\) \(\ds 2^0 \times 3^4\)
\(\ds \leadsto \ \ \) \(\ds \gcd \set {64, 81}\) \(=\) \(\ds 2^0 \times 3^0\)
\(\ds \) \(=\) \(\ds 1\)

$\blacksquare$


Sources

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