Here's how we arrive at that:

* Platinum (IV): This indicates platinum has a +4 oxidation state.

* Oxide: This refers to the oxygen anion (O²⁻) with a -2 oxidation state.

To balance the charges, we need two oxygen ions (2 x -2 = -4) to equal the +4 charge of the platinum ion.

Therefore, the formula is PtO₂.