# RPN vs O'der stack

The clearest difference is in-app purchases: RPN at none against O'der stack's 3. RPN also leads on iOS requirement (12.0 vs 15.6). O'der stack's advantage is update cadence (every 3 months vs every 9 months) and device support (3 vs 1). On price and ads there is nothing between them.

Both are free to download. O'der stack sells 3 one-off in-app purchases. RPN asks for nothing beyond the download.

RPN ships an update every 9 months, O'der stack every 3 months. The most recent releases landed on June 1, 2026 and September 13, 2026 respectively.

## The numbers

| Metric | RPN | O'der stack |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (3 ratings)](https://appshunter.io/ios/app/rpn-70-hd/id436127144/reviews)** | — |
| Number of ratings | **3** | — |
| Positive reviews | 86.7% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 9 months | **Every 3 months** |
| Monetization | Free | — |
| Size | 14 MB | 59 MB |
| Requires iOS | **12.0** | 15.6 |
| Devices | iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Willy Kunz](https://appshunter.io/developer/424873503) | [ICT Fractal Inc.](https://appshunter.io/developer/473613262) |

## What reviewers say

### RPN

[App page](https://appshunter.io/ios/app/rpn-70-hd/id436127144)

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.

**Highlights:** 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

**Features:** macOS Compatibility

**In-app purchases:** none


### O'der stack

[App page](https://appshunter.io/ios/app/oder-stack/id1449798272)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Free trial for 7 days. | Free | one-time |
| Activate for 1 month. | $0.99 | one-time |
| Activate for year. | $9.99 | one-time |


## Frequently asked questions

### Is RPN free?

RPN is free to download, with no in-app purchases.

### Is O'der stack free?

O'der stack is free to download, with in-app purchases available.

### Do RPN or O'der stack have ads?

Neither RPN nor O'der stack shows ads.

### Which is updated more often, RPN or O'der stack?

RPN ships an update every 9 months, and O'der stack every 3 months. Most recently, RPN was updated on June 1, 2026 and O'der stack on September 13, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*