RPNCalcSeries calculators are a series of specialized calculators sold separately. If you have more than one RPNCAlcSeries calculator, they will be managed and kept integrated in RPNCalcSeries environment. RPNCAlcSeries itself is the runtime environment where RPNCAlcSeries calculators run. RPNCalcSeries-12C+ emulates the functionalities of HP-12C Programmable Financial Calculator (HP-12C is a trademark of Hewlett Packard Co.),with some extra features.