Possible Duplicate:
Would like a proofreading of my proof
Prove that if $n$ is positive integer, then $n^2$ is divisible by $3$ with remainder either $0$ or $1$.
Possible Duplicate:
Would like a proofreading of my proof
Prove that if $n$ is positive integer, then $n^2$ is divisible by $3$ with remainder either $0$ or $1$.
Hint: $ 0^2=0\mod 3, $
$ 1^2=1\mod 3, $
$ 2^2=4=1\mod 3. $