Ammonium nitrite = NH\(_4\)NO\(_2\)

NH\(_4 ^+\): Let the oxidation number of Nitrogen = x

x + 4 = 1 \(\implies\) x = 1 - 4

x = -3

NO\(_2 ^-\): x - 4 = -1

x = -1 + 4 \(\implies\) x = +3.

The oxidation numbers for Nitrogen in Ammonium Nitrite = -3, +3.