# The Master Key System vs -48 Calculator

The clearest difference is review sentiment: -48 Calculator at 100% against The Master Key System's 25%. -48 Calculator also leads on rating (5.0 vs 3.3) and in-app purchases (none vs 1). The Master Key System's advantage is iOS requirement (8.0 vs 17.1). On price, ads, monetization model and device support there is nothing between them.

Both are free to download. The Master Key System sells 1 one-off in-app purchase. -48 Calculator asks for nothing beyond the download.

-48 Calculator holds the better App Store score, 5.0 against 3.3. Both are backed by a comparable volume of ratings — 7 and 24 respectively. Written reviews point the same way: 25% of The Master Key System's written reviews are positive against 100% of -48 Calculator's.

## The numbers

| Metric | The Master Key System | -48 Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.3 (7 ratings)](https://appshunter.io/ios/app/the-master-key-system-audio/id1380717052/reviews) | **[5.0 (24 ratings)](https://appshunter.io/ios/app/48-calculator/id6448708115/reviews)** |
| Number of ratings | 7 | **24** |
| Positive reviews | 25.0% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | — | Monthly |
| Monetization | Free | Free |
| Size | 49 MB | 37 MB |
| Requires iOS | **8.0** | 17.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Huong Nguyen](https://appshunter.io/developer/1342162705) | [Thomas McSorley](https://appshunter.io/developer/1685728168) |

## What reviewers say

### The Master Key System

[App page](https://appshunter.io/ios/app/the-master-key-system-audio/id1380717052)

This application provides an audio version of "The Master Key System," a personal development book focusing on New Thought principles. It features synchronized narration, allowing users to read and listen simultaneously, with exercises and Q&A sections for each chapter.

**Highlights:** Synchronized audio narration, Chapter exercises and Q&A, Adjustable font size and style, Night and day reading modes, Background audio playback, Text highlighting

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock All | $0.99 | one-time |


### -48 Calculator

[App page](https://appshunter.io/ios/app/48-calculator/id6448708115)

This app converts text into numerical values using various cipher dictionaries. It allows saving and searching phrases, calculating date differences, and analyzing public domain Bible texts and archived online posts.

**Highlights:** Text to numeric value conversion, Multiple cipher dictionaries, Save and search phrases, Date difference calculator, Analyze Bible texts, Analyze archived online posts

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

**In-app purchases:** none


## Frequently asked questions

### Is The Master Key System free?

The Master Key System is free to download, with in-app purchases available.

### Is -48 Calculator free?

-48 Calculator is free to download, with no in-app purchases.

### Which has better reviews, The Master Key System or -48 Calculator?

-48 Calculator is rated higher. The Master Key System averages 3.3 out of 5 from 7 ratings, while -48 Calculator averages 5.0 from 24 ratings.

### Do The Master Key System or -48 Calculator have ads?

Neither The Master Key System nor -48 Calculator shows ads.

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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.*