Slide Rule vs i41CX+
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Slide Rule
Simulates a mechanical analog computer for scientific and engineering calculations. Perform multiplication, division, roots, and trigonometric functions with a digital slide rule.
- Multiplication and division
- Square and cube roots
- Trigonometry functions
- Logarithm calculations
- Digital slide rule simulation
- Mechanical analog computer
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This app is a slide rule simulator. The slide rule (a.k.a. slipstick) is an mechanical analog computer which was formerly used for various scientific calculations, engineering design and surveying. It consists of three linear strips and a sliding cursor and is used for multiplication, division, square, cube, square root, cubic root, trigonometry, logarithm and so on. Please note that trigonometry and logarithm are not supported and the width of the scale is 1,000 pixels in this version.
i41CX+
This advanced RPN scientific calculator offers workstation-class Computer Algebra System (CAS) capabilities, going beyond traditional replicas. It provides access to an extensive library of modules and programs, enhanced with iOS features, customizable skins, and iCloud support for seamless data management.
- RPN logic with 4-element stack
- Extensive memory registers
- Over 400 built-in functions
- Computer Algebra System (CAS)
- Virtual thermal printer/plotter
- Access to HP-41 module library
- Customizable skins and keyboard overlays
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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.
Screenshots
Verdict
The clearest difference is price: Slide Rule at $0.99 against i41CX+'s $24.99. i41CX+'s advantage is rating (4.8 vs 1.0) and update cadence (every 5 weeks vs every 29 months). On ads, in-app purchases, monetization model 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
Slide Rule costs $0.99 and i41CX+ $24.99 up front. Neither carries in-app purchases, so what you see is what you pay.
i41CX+ holds the better App Store score, 4.8 against 1.0. That said, the two scores are not equally well evidenced: i41CX+ has 106 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 75% of Slide Rule's written reviews are positive against 91% of i41CX+'s.
Slide Rule ships an update every 29 months, i41CX+ every 5 weeks. The most recent releases landed on September 21, 2026 and September 25, 2026 respectively.
| Parameter | Slide Rule | i41CX+ |
|---|---|---|
| Price | $0.99 — better | $24.99 |
| Rating | 1.0 (1 ratings) | 4.8 (106 ratings) — better |
| Positive reviews | 75.0% of reviews | 91.3% of reviews — better |
| Number of ratings | 1 | 106 — better |
| Update frequency | Every 29 months | Every 5 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17.0 | 13.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 123 MB |
| Age rating | 4+ | 4+ |
| Developer | Masayuki Akamatsu | Antonio Lagana |
Customer experience
Slide Rule
i41CX+
Bugs and requests
Slide Rule
Not enough reviews yet to summarise bugs or 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
In-app purchases
Slide Rule
No in-app purchases
i41CX+
No in-app purchases









