RPN 28x Calc

Math can be fun.

Go to the App Store on iTunes

RPN 28x Calc in action

High Precision Arithmetics

Supports numbers with up to 38 significant digits.

Multiple Data Types

Real numbers, binary numbers, lists, arrays or vectors, matrices, names, strings and programs.

Interactive Stack Display

On iPad, the display expands to fill the screen. You can easily scroll and select your entries.

RPN 28x Calc

RPN 28x Calc is a programmable scientific calculator for iOS. It uses reverse-polish notation (RPN) for its operation and features a unique dynamic stack display.

You can operate with real numbers, binary numbers, names, strings, lists, arrays or matrices, and you can write programs to expand the functionality to your needs.

Advanced commands can be accessed via command pages, which open in a secondary panel (on iPad) or replace the regular panel (on iPhone). You can swipe across the button panels to navigate between the pages.

iPhone and iPad

RPN 28x Calc is a universal iOS app which can run on iPhone and iPad, whichever size you have, as long as you have iOS 11 or later.

There are two colour themes: the default "Black & Grey" theme and "Brown & Sand" which you can turn on in the settings. Check out the screen shots to see the two themes side-by-side.

RPN 28x Calc iPhone main screenshotRPN 28x Calc iPhone trigonmetry screenshotRPN 28x Calc iPhone statistics screenshotRPN 28x Calc iPhone binary numbers screenshotRPN 28x Calc iPhone binary numbers screenshotRPN 28x Calc iPhone stack reordering screenshotRPN 28x Calc iPhone sound and interface settings screenshotRPN 28x Calc iPhone X mask

Dynamic Stack

On iPhone, you can swipe the stack display down to see values on lower stack levels.

On iPad, the display automatically expands as you add more values to the stack. Once fully expanded, you can swipe down to see values on lower stack levels.

You can also re-order the levels or modify any of the values on the stack.

RPN 28x Calc reorder example


Use the rich command set to write your own programs.

Matrix Calculations

Work with large data sets using arrays and matrices.

iPad Multitasking

You can use the calculator in Slide Over or Split View alongside other apps on an iPad.

Variable viewer of RPN 28x Calc

Variable Viewer (iPad only)

You can browse all variables in a separate viewer. To make a variable available to a command, simply select it in the viewer and issue the command. Double-tap a variable to edit it.

Command & Results History (iPad only)

Select "Log" to display your command history. To place a value back onto the stack, double-tap it. Swipe upwards to reveal a panel of action buttons, i.e. to delete entries or to share the log.

Command Panels

On iPad, the side panel has a keyboard and three pages of commands. You can swipe across the panel to navigate between the pages.

Work With Operands

Tap an operand in the display to select it. Then issue a command which will use your selected operand.

User Guide

From the (i)nfo menu within the app, you can download the user guide with an introduction and a command reference.

Download PDF

See below for older versions.

RPN 28x Calc screenshot

Multiple Undos

You can restore previous stacks with the UNDO command. LAST restores the most recently used operands. With COMMAND, you can get back the most recently typed input.

Landscape Orientation

When you rotate your device, RPN 28x Calc re-adjusts its layout to fit the available screen area.

No Ads

No interruptions. RPN 28x Calc does not display ads. There are no rating requests.

RPN 28x Calc
RPN 28x Calc

iPhone and iPad $3.99
Version 3.0.2 (1802)
03 February 2019
Languages: English

iOS 11 or later.

Tested on iOS 12.

Latest News

Version 3.0 introcudes programming and matrices and supports iPad multitasking. Also runs on any iPhone with iOS 11 or later.

Version 2.1 adds action buttons to the command log. New command: ≠ and aliases: CHS, SQRT, and ==.

Version 2.0 adds a log and variable viewer.

Plans for future versions

  • User-definable buttons.
  • Complex numbers.
  • Arithmetic expressions.

Also Note

  • June 28 is Tau Day, celebrating the circle constant τ = 6.283185… (2π).
  • Pi Approximation Day is observed on July 22 (i.e. 22/7).
  • π was introduced as an abbreviation of the Greek word "periphery" (περιφέρεια)