Built for business, the LS-153TS features the innovative Cost Sell Margin (CSM) function: an easy-to-use feature operated by three keys – Cost, Sell and Margin. Simply enter any two of these values and the unknown variable is calculated instantly. Furthermore, a selectable switch enables you to change to a handy Tax function. You'll find that these practical features all but eliminate the need for complex formulas when it comes to performing many key business calculations. The LS-153TS offers a choice of power sources – either solar power or batteries.