Question

$(n+1)(n+2)$ is an even number

Answer 1

$\Rightarrow (n+1)(n+2)\to$ is an even NO

$\Rightarrow n^2+2n+2$

$n\Rightarrow$ even $\Rightarrow$ odd$\times$ even=even

$n=$odd $\Rightarrow$ even $\times$ odd=even