Plus42
5.0star
173 reviews
1K+
Downloads
Everyone
info
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.
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.
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Ratings and reviews
5.0
152 reviews
Zonn
- Flag inappropriate
May 21, 2023
The first program I've always installed on a new phone is Free42. I liked it so much I've donated money to keep the project alive. But I had no idea Plus42 existed. What I nice extension to the HP42s! I bought this within minutes of knowing of it's existence. Thanks Thomas for all your work over the years! (And trust me, it's been years. I remember when Thomas wasn't sure he was going to support Android, he wanted to wait and see if it stayed around long enough to make it worth his while. 🙂)
12 people found this review helpful
Thomas Okken
October 14, 2024
That was when I was still actively supporting Windows Mobile and PalmOS. It feels like ages ago. :-)
Dave Lindbergh
- Flag inappropriate
October 3, 2025
First calculator app that's actually BETTER than a HP-42S. My only complaint is the missed opportunity - why continue putting the soft key labels on the bottom of the display area, when on Android they can just as easily be placed directly on the (otherwise blank) buttons?
Thomas Okken
October 3, 2025
My main reason for not doing that, apart from esthetic preference, is that the bottom row of the screen isn't always used for the menu, so displaying the stack-only view, or a full-screen plot, would get messy. But another approach could be to just remove the top row of keys, since you can tap the soft keys in the display directly as well.
Dan McCullough
- Flag inappropriate
May 5, 2022
I liked free42 but needed more than 2 lines, one of which was more often than not used for menu options. This app is better than I could have even hoped, with fully configurable lines up to 99, and adds built in unit conversions, directories, and several other RPL like niceties, while sticking with the simpler programming and functionality of the 42s model. Very happy so far with what is only version 1!
9 people found this review helpful
What’s new
Fixed crash in menu logic.
App support
About the developer
Thomas Okken
thomasokken@gmail.com
Willem Barentszweg 9F
1212 BK Hilversum
Netherlands