i41CX+ vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i41CX+
This advanced RPN scientific calculator offers workstation-class CAS capabilities, emulating the HP-41CX with extensive modules and programs. It features a virtual thermal printer/plotter, iCloud support, and a full-screen text editor for enhanced productivity.
- RPN logic with 4-element stack
- Virtual thermal printer/plotter
- Workstation-class Computer Algebra System (CAS)
- Full HP-41CX emulation and module support
- Programmable with unlimited lines
- iCloud syncing and extensive import/export
- Full-screen text editor with configurable keyboard
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i41CX+ is an advanced programmable and expandable RPN scientific calculator with a virtual thermal printer/plotter and workstation-class CAS capabilities that is far beyond a mere replica of the original. In addition to being functionally equivalent to the world-renowned HP-41CX and providing access to its entire library of modules and programs, i41CX+ is enhanced with iOS and hardware features, keyboard overlays, rich set of import and export capabilities, traditional and upbeat diverse set of skins, complete color control, iCloud support, and much more. The i41CX+ CAS is a full implementation of REDUCE. It's like having Mathematica or the computational engine of Wolfram Alpha in your pocket and, best of all, it runs natively so no internet connection is required. The CAS is fully programmable and provides the ability to reuse previous results in computations. Moreover, the CAS has full access to the calculator registers so it is possible to combine RPN programs with CAS programs. This is the finest and most powerful scientific/engineering/financial calculator for iOS devices bar none. CALCULATOR FEATURES: • RPN logic with a 4 element deep memory stack • 319 main and 600 extended memory registers • Over 400 built-in functions, including over 100 functions created specifically for i41CX+ • Time, calendar, alarm, and stopwatch functions • Four module ports provide access to HP-41 expansion pacs • Rich set of functions and algorithms: numerical, mathematical, statistical, complex, matrix, numerical integration, curve fitting, solutions to equations, and much more • Powerful, flexible, and programmable Computer Algebra System (CAS) supporting symbolic, arbitrary precision, scalar, vector and matrix algebra calculations, 2D/3D plotting, and much more • Full-screen text editor with configurable font style and size, color scheme, a user configurable macro keyboard, and a numerical keyboard • Access to the entire HP-41 library of solutions for science, mathematics, statistics, engineering, business, financial, surveying, medicine, real estate, and many other domains • Programmable - virtually unlimited number of lines • User definable keyboard • Ability to operate the calculator using a Bluetooth keyboard • Device integration: external display mirroring, copy and paste, in-app mail, system keyboard, GPS, accelerometer, digital compass, time and date synchronization, AirPrint, and much more • Virtually unlimited data and program storage capacity using the device's flash memory for local storage • Import/export data, programs, overlays, modules, etc. via the web, email, and iTunes file sharing • iCloud syncing of files and preference settings • iOS 8 Notification Center widget • 43 available keyboard overlays and support for user created overlays • Sound support including synthetic tones and interface sounds • Support for calculator skins and optional mini stack display • Adjustable calculator speed, sound volume, and display colors • Usage & Examples table with usage tips and examples • Quick Reference Guide of all built-in functions • CAS Quick Reference with all built-in functions, operators, switches, and packages • Beautiful and clean user interface PRINTER FEATURES: • Support for printing, plotting, graphics, and special characters • User configurable and programmable print color • Export printer output via email, clipboard, or AirPrint • Ability to save a JPEG image of the paper roll to the device's photo album *********************************************************** A comprehensive FAQ and Mini-Manual are available at http://alsoftiphone.com/i41CXplus. Please don't hesitate to use the "Contact Us" link there if you cannot find the answers or information that you seek. Thank you.
RPN
This app provides a photo-realistic simulation of a rare 1974 financial calculator, offering full functionality for loan amortization, saving plans, and depreciation. It features an authentic design with animated keys and an optional live register view.
- Photo-realistic design
- Live register view
- Animated keys with sound
- Full HP-70 function implementation
- Cut/copy/paste display value
- Built-in manual with examples
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RPN-70 HD is a complete, photo-realistic simulation of the financial hand-held calculator HP-70 from 1974. It handles loan amortization, saving plans, depreciation, and much more with ease. What users said: "Hard to find a decent calculator on iPad, try this one." "I don't normally write reviews but RPN-70 is just too fantastic to not get excited about. Apple should list this app under their Education category in the App Store and make it a must have for every college bound student. It is the best HP emulator in the market." "An incredibly well-engineered calculator app, and free, to boot!" "This is a really cool Financial calculator. Just like using the original HP-70. Accurate to the penny." Features: • Photo-realistic look based on an existing device • "Live" register view in landscape mode • Animated keys with click sound (adjustable volume) • All functions and operations of the HP-70 fully implemented • Simulation of the HP-70's computation time (optional) • Correct wrong number entries by swiping left across the display • Cut/copy/paste of display value • Visual indicators keep track of stored input parameters (optional) • Stack shown right below display (optional) • 10 non-volatile memory registers (optional) • Built-in short manual with many examples The HP-70 was discontinued after just one year. It is one of the rarest calculators, hard to find in any condition. NOTE: RPN-70 HD is a faithful simulation of a vintage HP-70 calculator, as has been verified against a real device using the examples in the Applications Cookbook section of the HP-70 manual. In certain cases, what may appear like a bug of the app is actually an idiosyncrasy of the HP-70. IMPORTANT: The HP-70 requires exactly three input parameters from the top-row keys, at least one of them being either "n" or "i". In other words, you can't use PMT, PV, and FV as input parameters simultaneously. A version for the iPhone named "RPN-70 SD" is also available. Visit the website: www.cuveesoft.ch
Screenshots
Verdict
The clearest difference is price: RPN at Free against i41CX+'s $24.99. RPN also leads on rating (5.0 vs 4.8) and iOS requirement (12.0 vs 16.0). i41CX+'s advantage is update cadence (every 2 days vs every 9 months) and ratings volume (108 vs 3). On ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
RPN is free to download; i41CX+ costs $24.99 up front. Neither carries in-app purchases, so what you see is what you pay.
RPN holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: i41CX+ has 108 ratings behind it against 3, so its average is the more settled of the two. Written reviews complicate that: 91% of i41CX+'s written reviews are positive against 83% of RPN's, so the app with the better star average is not the one people write more warmly about.
i41CX+ ships an update every 2 days, RPN every 9 months. The most recent releases landed on November 12, 2026 and November 4, 2026 respectively.
| Parameter | i41CX+ | RPN |
|---|---|---|
| Price | $24.99 | Free — better |
| Rating | 4.8 (108 ratings) | 5.0 (3 ratings) — better |
| Positive reviews | 91.4% of reviews — better | 83.3% of reviews |
| Number of ratings | 108 — better | 3 |
| Update frequency | Every 2 days — better | Every 9 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad — better | iPad |
| Requires iOS | 16.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 124 MB | 14 MB |
| Age rating | 4+ | 4+ |
| Developer | Antonio Lagana | CuVee Software |
Customer experience
i41CX+
RPN
Bugs and requests
i41CX+
Reported bugs
2 issues- Issues with the 41Z math module producing garbled output
- Scaling problems with overlays
Requested features
4 requests- Landscape mode for better button size
- Haptic feedback for button presses
- Ability to load and save programs/modules via cloud/email
- Macros or scripting support
RPN
Not enough reviews yet to summarise bugs or requests.
In-app purchases
i41CX+
No in-app purchases
RPN
No in-app purchases








