##MnO_2##

To write the chemical formula for Manganese (IV) Oxide, you must make sure to balance the charges.

The roman numeral IV in front of manganese tells us that it is oxidizing at ##4^+##. Looking at the table, oxygen is a group 16 element which means it oxidizes at a ##2^-## state, To neutralize the oxidation number of manganese, two atoms of oxygen should be added to achieve the final compound ##MnO_2##.