This smart, 12-digit desktop calculator sets new standards â€“ in style, efficiency and environmental accountability. It features a large and clear LCD display panel made using 100% residual material from the manufacture of Canon Digital Camera prism lenses. This maximises resource efficiency and reduces wastage â€“ making the X MARK 1 the calculator of choice for responsible executives, professionals and environment conscious individuals.Work out your profit margins automatically using separate cost-sell-margin keys, without the need for complex formulae. Itâ€™s the easiest way to simplify complex calculations and save time. Other functions include a Grand Total memory as well as shift, percentage, sign change and square root keys. A key roll over function allows speedy entry of figures without keys blocking.