Problem
NT-B2-M03-P006 Order Criterion
#6
★★★☆☆ Level 3 of 5
Let \( \gcd(a,m)=1 \) and \(d=\operatorname{ord}_m(a)\). Prove that \(a^k\equiv1\pmod m\) if and only if \(d\mid k\).
Divide \(k\) by \(d\) with remainder.
Let \(k=qd+r\), where \(0\le r
This is the main fact of the module and should be stated explicitly.