# Even or odd Mental calculation vs Tchisla

The clearest difference is ads: Tchisla at none against Even or odd Mental calculation's shown. Tchisla also leads on update cadence (monthly vs every 23 months) and iOS requirement (8.0 vs 15.0). Even or odd Mental calculation's advantage is review sentiment (100% vs 88%). On price, in-app purchases, monetization model and device support there is nothing between them.

Both are free to download. Even or odd Mental calculation sells 1 one-off in-app purchase and Tchisla sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Even or odd Mental calculation ships an update every 23 months, Tchisla monthly. The most recent releases landed on November 1, 2026 and November 2, 2026 respectively.

## The numbers

| Metric | Even or odd Mental calculation | Tchisla |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.9 (154 ratings)](https://appshunter.io/ios/app/tchisla-number-puzzle/id1100623105/reviews)** |
| Number of ratings | — | **154** |
| Positive reviews | **100.0% of reviews** | 87.7% of reviews |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 23 months | **Monthly** |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 68 MB | 25 MB |
| Requires iOS | 15.0 | **8.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Iker Vazquez](https://appshunter.io/developer/1032978250) | [HORIS INTERNATIONAL LIMITED](https://appshunter.io/developer/646324304) |

## What reviewers say

### Even or odd Mental calculation

[App page](https://appshunter.io/ios/app/even-or-odd-mental-calculation/id1032978251)

Test your mental math skills by quickly determining if the result of an on-screen operation is even or odd. Earn more points for faster answers and challenge friends to see who has the quickest mind. The difficulty increases as you progress.

**Highlights:** Timed mental calculation challenges, Score tracking for personal bests, Speed-based scoring system, Increasing difficulty levels, Multiplayer comparison

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full version upgrade | $0.99 | one-time |


### Tchisla

[App page](https://appshunter.io/ios/app/tchisla-number-puzzle/id1100623105)

This app challenges you to represent numbers as arithmetic expressions using only digits 1-9. It offers various operations, including roots, powers, and factorials, to find optimal solutions. Improve your mental math skills through engaging puzzles and competitive modes.

**Highlights:** Represent numbers as arithmetic expressions, Use digits 1-9, Standard arithmetic operations (+, -, *, /), Advanced operations (√, ^, !), Practice mode with tutorial, Competitive modes with leaderboards, Gallery for tracking progress and solutions

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Extended gallery | $1.99 | one-time |

**What reviewers like**

- 🧠 Great brain workout
- 🎨 Beautiful design
- 💡 Interesting puzzles
- 👍 Addictive and fun
- 🆓 Free and ad-free

**What reviewers complain about**

- 🐛 Frequent crashes
- 📉 Server issues for contests
- 🤔 Solutions not accepted
- ⚠️ Solutions marked as non-optimal
- ❌ Lost results after reinstallation

**Reported bugs**

- App crashes frequently
- Daily contest server not working
- Incorrect score recording in contests
- Solutions not recorded in contests
- Yellow marks on solutions revoked after reinstallation

**Requested features**

- Add sound effects for gamification
- Option to turn off hints
- Harder modes for gallery puzzles
- Sync solutions across devices (iCloud, Game Center)
- Allow multiple solutions to be displayed


## Frequently asked questions

### Is Even or odd Mental calculation free?

Even or odd Mental calculation is free to download, with in-app purchases available.

### Is Tchisla free?

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

### Do Even or odd Mental calculation or Tchisla have ads?

Even or odd Mental calculation shows ads; Tchisla does not.

### Which is updated more often, Even or odd Mental calculation or Tchisla?

Even or odd Mental calculation ships an update every 23 months, and Tchisla monthly. Most recently, Even or odd Mental calculation was updated on November 1, 2026 and Tchisla on November 2, 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.*