A vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
A
This application simplifies the design of RC beams, offering detailed calculation steps for confidence in results. It initially supports ACI 318 building codes in US and Metric units, with plans to add more design codes.
- Simplified RC beam design
- Detailed calculation steps
- ACI 318 Building Code support
- US and Metric units
- Future design code additions
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The A-Beam+ is the extension of the previous A-Beam app that make the design of the RC beam easy and as simple as using the normal calculator. But behind the simplicity the app also provide the very details of the calculation in every step to make you confident with the calculation result. The initial version support for the "ACI 318" Building Code both US & Metric (SI-Metric and MKS-Metric) units with more other design codes will be added.
RPN
This app is a photo-realistic simulation of a classic Hewlett-Packard programmable scientific calculator from the 1970s. It includes a 100-hour digital timer, clock functions, and original HP programs.
- Photo-realistic look-and-feel
- Programmable with conditional branching
- 100-hr timer and 12/24-hr clock
- Original HP programs built-in
- Extended features for enhanced usability
- Sharing via email, AirDrop, and more
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RPN-55 SD is the first photo-realistic simulation for the iPhone of Hewlett-Packard's low-cost alternative to the famous HP-65 programmable scientific calculator. Produced from 1975 through 1977, it was the "Merlin" member of the classic HP calculator series, priced at $395. HP claimed that it featured "(...) more pre-programmed functions than any other scientific pocket calculator in the world." A main feature of the HP-55 was a crystal-controlled 100-hr digital timer with the ability to store times while the timer was running and later recall them. On RPN-55 SD the timer may also act as a 12-hr or 24-hr clock, including date and weekday display. While the simulator works just like the original calculator – except being much faster and having twice the program memory – you can turn on extended features to make it even more enjoyable to use. RPN-55 SD comes complete with original HP programs built in. Features: • Photo-realistic look-and-feel • Vintage mode or Extended mode • Programmable (99 steps), conditional branching • Insert and delete steps with automatic address correction • Delete range of steps • Subroutines (4 levels) • 20 registers, "continuous", with unrestricted store/recall arithmetic • "Live" register view • Program listing view • Program library view • Store and retrieve any number of programs • 100-hr timer supporting 10 split times and 12/24-hr clock mode with date • Swap unit conversions with additional functions, e.g. hyperbolics • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • 112 programs pre-installed Calculator functions: • Statistics (linear regression, mean, standard deviation, correlation coefficient, x- and y-estimates) • Trigonometric functions (degrees, radians, grads) • Polar/rectangular conversions • Inverse, square root, logarithm, exponential, pi • Storage arithmetic (store and recall) • Percent, absolute, integer, fractional value, round • Factorial • Random number • Unit and hours conversions Details: cuveesoft.ch/rpn55
Screenshots
Verdict
The clearest difference is review sentiment: RPN at 100% against A's 50%. RPN also leads on rating (5.0 vs 1.0) and update cadence (every 3 months vs every 9 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
A costs $4.99 and RPN $1.99 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 1.0. Both are backed by a comparable volume of ratings — 2 and 8 respectively. Written reviews point the same way: 50% of A's written reviews are positive against 100% of RPN's.
A ships an update every 9 months, RPN every 3 months. The most recent releases landed on August 27, 2026 and September 6, 2026 respectively.
| Parameter | A | RPN |
|---|---|---|
| Price | $4.99 | $1.99 — better |
| Rating | 1.0 (2 ratings) | 5.0 (8 ratings) — better |
| Positive reviews | 50.0% of reviews | 100.0% of reviews — better |
| Number of ratings | 2 | 8 — better |
| Update frequency | Every 9 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 18.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 53 MB | 17 MB |
| Age rating | 4+ | 4+ |
| Developer | Jutarus Ratanasethakul | CuVee Software |
Customer experience
A
RPN
In-app purchases
A
No in-app purchases
RPN
No in-app purchases









