Simple RPN combines the most essential RPN features with the same stack behavior found in HP calculators. The calculator works in either portrait or landscape mode, supports international number formats, and has continuous memory for all registers. In addition to the functions shown in the screenshots, you can choose the number of decimal places to show by pressing [ f ] + [ any number ] and use the ten storage registers by pressing [ f ] + [ STO ] or [ RCL ] + [ any number ].
This calculator is a labor of love that I created to suit my tastes, and I use it every day. Every aspect of it, from the operational logic to the graphic design, has benefitted from meticulous attention to detail. Enjoy the RPN goodness!