Write the chemical formula of Potassium permanganate in a step-by-step manner.

Step 1 — Write each symbol with its valency

$\text{K}^{1+} \phantom{\nearrow} \text{MnO}_4^{1-}$

Step 2 — Interchange the valencies

$\overset{\phantom{2}{1}}{\text{K}} \space {\searrow}\mathllap{\swarrow} \space \overset{1}{\text{MnO}$4} \Rightarrow \underset{\phantom{1}{1}}{\text{K}} \space {\searrow}\mathllap{\swarrow} \space \underset{1}{\text{MnO}4} \\[0.5em]

Step 3 — Write the interchanged number & hence the formula

Therefore, we get

Formula of Potassium permanganate : $\bold{KMnO_4}$