What's New
Re-compiled to support Android 9
About HP21 scientific RPN calculator Android App
The HP-21 was a scientific calculator produced by Hewlett-Packard between 1975 and 1978. It was designed as a replacement for the HP-35, and was the first from so called Second Generation Handheld Calculators.
As with most HP calculators then and now, the HP-21 used RPN entry logic, with a four-level stack. It also had a single user-accessible memory register. A shift key provided access to functions whose legends were printed on the fronts of the tall trapezoidal keys.
To enhance practical usability, display was modified to show both X and Y register. Also I have eliminated mechanical DEG/RAD switch and moved the function under DSP button.
HP21 has few big enough buttons to be used comfortably on mobile devices.
Other Information:
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This version of HP21 scientific RPN calculator Android App comes with one universal variant which will work on all the Android devices.
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If you are looking to download other versions of HP21 scientific RPN calculator Android App, We have 8 versions in our database. Please select one of them below to download.
