# Zetamac Arithmetic Practice vs 66 Days

The clearest difference is in-app purchases: Zetamac Arithmetic Practice at none against 66 Days's 2. Zetamac Arithmetic Practice also leads on review sentiment (83% vs 50%) and update cadence (daily vs every 10 days). 66 Days's advantage is ratings volume (258 vs 19). On price, rating, ads and device support there is nothing between them.

Both are free to download. 66 Days sells 2 in-app purchases, starting at $15.99 per month. Zetamac Arithmetic Practice asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 4.7 for Zetamac Arithmetic Practice against 4.8 for 66 Days. That said, the two scores are not equally well evidenced: 66 Days has 258 ratings behind it against 19, so its average is the more settled of the two. Written reviews are what separate them: 83% of Zetamac Arithmetic Practice's written reviews are positive against 50% of 66 Days's.

Zetamac Arithmetic Practice ships an update daily, 66 Days every 10 days. The most recent releases landed on October 27, 2026 and October 23, 2026 respectively.

## The numbers

| Metric | Zetamac Arithmetic Practice | 66 Days |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.7 (19 ratings)](https://appshunter.io/ios/app/zetamac-arithmetic-practice/id6737153617/reviews) | **[4.8 (258 ratings)](https://appshunter.io/ios/app/66-days-ai-interview-prep/id6752681422/reviews)** |
| Number of ratings | 19 | **258** |
| Positive reviews | **83.3% of reviews** | 50.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Daily** | Every 10 days |
| Monetization | **Free** | Freemium |
| Size | 1 MB | 110 MB |
| Requires iOS | 17.5 | **17.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Joseph Ma](https://appshunter.io/developer/1774979062) | [Uru Technologies, LLC](https://appshunter.io/developer/1840551197) |

## What reviewers say

### Zetamac Arithmetic Practice

[App page](https://appshunter.io/ios/app/zetamac-arithmetic-practice/id6737153617)

This app offers mental math practice tailored for quantitative finance professionals. It focuses on improving calculation speed and accuracy for complex numerical problems.

**Highlights:** Mental math practice, Quantitative finance focus, Calculation speed improvement, Accuracy enhancement, Numerical problem solving

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

**In-app purchases:** none


### 66 Days

[App page](https://appshunter.io/ios/app/66-days-ai-interview-prep/id6752681422)

Master banking and consulting interviews with daily AI-powered practice. Track your progress on a 66-day journey with personalized feedback on technical, behavioral, and case questions. Improve your resume and gain confidence for top firms.

**Highlights:** AI interview coach with personalized feedback, Daily drills for behavioral, technical, and case questions, 66-day progress heat map, Resume checker, Excel and valuation tools, Analytics dashboard

**Features:** Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 66 Days Prep Pro | $15.99 | per month |
| 66 Days Prep Pro | $49.99 | per year |


## Frequently asked questions

### Is Zetamac Arithmetic Practice free?

Zetamac Arithmetic Practice is free to download, with no in-app purchases.

### Is 66 Days free?

66 Days is free to download, with in-app purchases available.

### Which has better reviews, Zetamac Arithmetic Practice or 66 Days?

66 Days is rated higher. Zetamac Arithmetic Practice averages 4.7 out of 5 from 19 ratings, while 66 Days averages 4.8 from 258 ratings.

### Do Zetamac Arithmetic Practice or 66 Days have ads?

Neither Zetamac Arithmetic Practice nor 66 Days shows ads.

### Which is updated more often, Zetamac Arithmetic Practice or 66 Days?

Zetamac Arithmetic Practice ships an update daily, and 66 Days every 10 days. Most recently, Zetamac Arithmetic Practice was updated on October 27, 2026 and 66 Days on October 23, 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.*