$1.$ Return on investment $($ROl$)$ equals margin multiplied by sales$\mathrm{.}2.$ When used in return on investment $($ROI$)$ calculations, turnover equals sales divided by average operating assets$\mathrm{.}3.$ Net operating income is income after interest and taxes$\mathrm{.}4.$ An advantage of using ROl to evaluate performance is that it encourages the manager to reduce the investment in operating assets as well as increase net operating income.