Claim:⟦a⟧ is a unit mod m if and only if gcd(a,m) = 1

From CS2800 wiki
If [math]\href{/cs2800/wiki/index.php/Modular_number}{⟦a⟧} \href{/cs2800/wiki/index.php/%5Cin}{\in} \href{/cs2800/wiki/index.php/%E2%84%A4_m}{ℤ_m} [/math], then [math]\href{/cs2800/wiki/index.php/Modular_number}{⟦a⟧} [/math] is a unit if and only if [math]\href{/cs2800/wiki/index.php/Gcd}{gcd}(a,m) = 1 [/math].