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About this app
Plus42 is an advanced scientific programmable calculator, based on Free42. Free42, in turn, is a complete re-implementation of the HP-42S scientific programmable RPN calculator, which was made from 1988 until 1995 by Hewlett-Packard. Free42 is a complete rewrite and contains no HP code whatsoever. Plus42 builds on Free42 and adds: Algebraic expressions modeled after those used on the HP-27S and HP-17B/19B; attached units and unit conversions modeled after those used on the HP-48/49/50 series; directories for more organized storage of programs and variables; a larger display, with 8 rows and 22 columns (131x64 pixels) by default, which the user may resize at will; time value of money and amortization schedules; and two-dimensional plotting of functions, with ability to zoom and pan, and find integrals and roots from points in the plot.
What's new
Version 1.5.3 · Nov 11, 2026
The unit resolution logic would look for user-defined units before looking for prefixed built-in units. User can now control which one is on top when LTOP and ATOP are both turned on. In the programmable menu, pressing ▲ or ▼ if they hadn't been assigned would cause an Internal Error. Some text handling fixes for Copy and Paste. Functions invoked using direct XEQ mapping in skins now have fewer side effects.
