Restklassenringe (Z)/mod 6/Multiplikationstafel

$\begin{array}{ccccccc}*& 0& 1& 2& 3& 4& 5\\ 0& 0& 0& 0& 0& 0& 0\\ 1& 0& 1& 2& 3& 4& 5\\ 2& 0& 2& 4& 0& 2& 4\\ 3& 0& 3& 0& 3& 0& 3\\ 4& 0& 4& 2& 0& 4& 2\\ 5& 0& 5& 4& 3& 2& 1\end{array}$