Plus42 4+
Enhanced HP-42S Calc Simulator
Thomas Okken
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- $9.99
Screenshots
Description
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 1.2.6
Fixed crash when saving an equation without having modified it. This bug was introduced in the previous release.
Improvements in error handling when evaluating equations.
Ratings and Reviews
Love This
In college I was an HP41C user. Once in my first engineering job I switched to the HP42S which has served me well over my 30+ year career. Once iPhones became a thing, I loaded Thomas’s Free42 and have been using that for a couple decades. I still have a real 42S on my desk for daily use. I recently purchased an HP Prime which is a lovely calculator but it’s just not completely comfortable to use. Switching to Thomas’s Plus42 feels really comfortable and adds lots of lovely features. I will likely purchase a SwissMicro DM42 to be used as my daily desk calc so that my phone app and physical desk calc are similar. That would send the 42S to the vintage calc cabinet. Honestly having this on my phone is massively so functional it’s hard to justify even owning a physical calc but there are times at the desk when it’s nice to grab the physical unit with tactile keys that can’t be interrupted with alerts :-). This is a beautiful upgrade to the free42. Thanks Thomas!
What a delight!
I can’t believe I missed Thomas Okken’s free42 and plus42 projects until now, over 20 years after his first release it appears. It’s been a joy to get reacquainted with RPN and now have the same calculator on my phone, which I have on me all the time, as I have at my desk in physical form via SwissMicros’ DM42n that just arrived. Having a physical calculator at my fingertips that I love to use is something I haven’t experienced in probably 30 years, since college. The astro navigation and conversion apps I pulled down and loaded from Thomas’ website this morning is what prompted me to write this review. Thank you Thomas for this gift to us all! You’ve left no detail out for someone like me.
Beautiful and functional at the same time
Thomas has done an outstanding job on this app! It is not only the most beautiful calculator app out there, but it’s also the most powerful and functional of any of the HP inspired calculator app. The graphics are outstanding and the “extras” that were added in addition to the 42s standard makes the app even more appealing.
If you know how to use a RPN calculator, this IS the one to have and use. If you don’t know how to use a RPN calculator, learn how and buy this.
I always carry my phone, but rarely my physical DM42 or “real” 42s.
You won’t regret getting this app.
Congratulations Thomas for all the work you have done over the years relating to the 42. You should be proud.
App Privacy
The developer, Thomas Okken, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.
Data Not Collected
The developer does not collect any data from this app.
Privacy practices may vary, for example, based on the features you use or your age. Learn More
Information
- Seller
- Thomas Okken
- Size
- 12 MB
- Category
- Utilities
- Compatibility
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- iPhone
- Requires iOS 12.0 or later.
- iPad
- Requires iPadOS 12.0 or later.
- iPod touch
- Requires iOS 12.0 or later.
- Apple Vision
- Requires visionOS 1.0 or later.
- Languages
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English
- Age Rating
- 4+
- Copyright
- © 2004-2025 Thomas Okken
- Price
- $9.99
Supports
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Family Sharing
Up to six family members can use this app with Family Sharing enabled.