What is $\mathbb{Z_{n}}\left [ x \right ]$ 
Question: Show that $\mathbb{Z_{n}}\left [ x \right ]$ has characteristic $n$.

What does $\mathbb{Z_{n}}\left [ x \right ]$ stands for? I'm very sure this is not the gaussian ring.

It's the same thing as $(\mathbb{Z} / n\mathbb{Z})[x]$, the ring of polynomials with coefficients being the integers $mod$ $n$.
