What is the oxidation number of nitrogen in NO_2?

$\text{N(+IV)}$.
Do this for ${\text{NO}}_{2}$, and we get $\text{N(+IV)}$.
Can you determine oxidation numbers for nitrogen in ${\text{N"_2"O}}_{5}$, $\text{NO}$, and $\text{N"_2"O}$?