# Smart Adding Machine vs HP15C

The clearest difference is update cadence: Smart Adding Machine at every 3 weeks against HP15C's every 6 months. Smart Adding Machine also leads on price ($3.99 vs $4.99). HP15C's advantage is iOS requirement (15.6 vs 17.0). On ads, in-app purchases and device support there is nothing between them.

Smart Adding Machine costs $3.99 and HP15C $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Smart Adding Machine ships an update every 3 weeks, HP15C every 6 months. The most recent releases landed on October 11, 2026 and October 13, 2026 respectively.

## The numbers

| Metric | Smart Adding Machine | HP15C |
| --- | --- | --- |
| Price | **$3.99** | $4.99 |
| Rating | — | **[2.7 (3 ratings)](https://appshunter.io/ios/app/hp15c-scientific-calculator/id6741306693/reviews)** |
| Number of ratings | — | **3** |
| Positive reviews | — | 33.3% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 6 months |
| Monetization | — | Paid |
| Size | 0 MB | 24 MB |
| Requires iOS | 17.0 | **15.6** |
| Devices | iPhone, iPad, Mac | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Harry Detrick](https://appshunter.io/developer/1698895959) | [FERMAVE](https://appshunter.io/developer/1743250649) |

## What reviewers say

### Smart Adding Machine

[App page](https://appshunter.io/ios/app/smart-adding-machine/id6452400755)

**In-app purchases:** none


### HP15C

[App page](https://appshunter.io/ios/app/hp15c-scientific-calculator/id6741306693)

Relive the classic computing experience with a vintage scientific calculator. This app emulates a beloved 90s model, offering a nostalgic and functional tool for calculations.

**Highlights:** Vintage scientific calculator emulation, Classic 90s design, Functional for scientific calculations, Nostalgic user experience

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

**In-app purchases:** none


## Frequently asked questions

### Is Smart Adding Machine free?

Smart Adding Machine costs $3.99, with no in-app purchases.

### Is HP15C free?

HP15C costs $4.99, with no in-app purchases.

### Do Smart Adding Machine or HP15C have ads?

Neither Smart Adding Machine nor HP15C shows ads.

### Which is updated more often, Smart Adding Machine or HP15C?

Smart Adding Machine ships an update every 3 weeks, and HP15C every 6 months. Most recently, Smart Adding Machine was updated on October 11, 2026 and HP15C on October 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.*