Solution
= Solution
Take \b[$R=\mathbb Z/4\mathbb Z$], a <quotient ring> with four residue classes. The class $\overline2$ is nonzero but $\overline2\,\overline2=\overline0$. Thus $R$ has a <zero divisor> and is not an <integral domain>.
= Solution
Take \b[$R=\mathbb Z/4\mathbb Z$], a <quotient ring> with four residue classes. The class $\overline2$ is nonzero but $\overline2\,\overline2=\overline0$. Thus $R$ has a <zero divisor> and is not an <integral domain>.