What are Iron III oxide oxidation numbers?

You have answered the question for yourself.!!!!!

Iron (III) Oxide [ Fe2O3] has the oxidation number of '3'. Written in Roman Numerals ' III ' .

An atom of iron has 6 electrons in its outer most energy (valence) shell. Of these six electrons only '3' are involved in combining with another atoms. This other '3' remain uncombined.

Similarly Iron (II) Oxide

NB Iron as all the other Transition [ 'd' block ] elements, exhibits variable oxidation numbers.

NNB When you read Roman Numerals in a chemical name formula, it indicates the oxidation state.

NNNB Archaically Iron(II) oxide is Ferrous Oxide , and Iron(III) oxide is Ferric oxide.

NNNNB Potassium permanganate has the manganese in oxidation state '7', written as Potassium manganate(VII) [ KMnO4] .