# Quick mental calculation vs Digit Invader Calculator

The clearest difference is ads: Digit Invader Calculator at none against Quick mental calculation's shown. Quick mental calculation's advantage is iOS requirement (12.0 vs 17.6). On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Quick mental calculation ships an update every 11 days, Digit Invader Calculator every 9 days. The most recent releases landed on October 26, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | Quick mental calculation | Digit Invader Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.8 (12 ratings)](https://appshunter.io/ios/app/digit-invader-calculator/id6743176325/reviews)** |
| Number of ratings | — | **12** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 11 days | **Every 9 days** |
| Monetization | — | Free |
| Size | 21 MB | 5 MB |
| Requires iOS | **12.0** | 17.6 |
| Devices | iPhone, iPod | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [ERX](https://appshunter.io/developer/513941286) | [Daniel Fu Keung Kwan](https://appshunter.io/developer/1801804499) |

## What reviewers say

### Quick mental calculation

[App page](https://appshunter.io/ios/app/quick-mental-calculation/id841970890)

**Features:** macOS Compatibility

**In-app purchases:** none


### Digit Invader Calculator

[App page](https://appshunter.io/ios/app/digit-invader-calculator/id6743176325)

This app combines a functional calculator with a retro arcade game inspired by classic calculator interfaces. It offers automatic game saving, a high score list, and multitasking support on iPads. A scaled-down version is also available for Apple Watch.

**Highlights:** Retro calculator game, Basic calculator functions, Automatic game save, High score list, iPad Stage Manager support, Apple Watch version

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Quick mental calculation free?

Quick mental calculation is free to download, with no in-app purchases.

### Is Digit Invader Calculator free?

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

### Do Quick mental calculation or Digit Invader Calculator have ads?

Quick mental calculation shows ads; Digit Invader Calculator does not.

### Which is updated more often, Quick mental calculation or Digit Invader Calculator?

Quick mental calculation ships an update every 11 days, and Digit Invader Calculator every 9 days. Most recently, Quick mental calculation was updated on October 26, 2026 and Digit Invader Calculator on October 28, 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.*