OPie RPN Calculator app for iPhone and iPad

This is a combination RPN scientific calculator, RPN basic calculator, equation plotter, one-button statistics, linear equation solver, and unit converter.

After entering a lot of numbers onto the stack (useful for entering data for statistics), you can quickly remove or reorder those numbers by going into the E-Stack Editor.

The linear equation solver will solve up to 6 simultaneous equations.

Easily plot up to 8 equations from the Graph page.  

The unit converter page converts length, area, temperature, volume, weight, angle, digital storage, energy, pressure, force, time, electric current, speed, and luminance.

Note: swipe down on the keyboard to hide the tab bar and swipe up to display the tab bar.