# Euclidea vs Even or odd Mental calculation

The clearest difference is ads: Euclidea at none against Even or odd Mental calculation's shown. Euclidea also leads on update cadence (every 3 months vs every 23 months) and iOS requirement (8.0 vs 15.0). On price, in-app purchases, monetization model and device support there is nothing between them.

Both are free to download. Euclidea sells 6 one-off in-app purchases and Even or odd Mental calculation sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Euclidea ships an update every 3 months, Even or odd Mental calculation every 23 months. The most recent releases landed on October 29, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | Euclidea | Even or odd Mental calculation |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.8 (938 ratings)](https://appshunter.io/ios/app/euclidea/id927914361/reviews)** | — |
| Number of ratings | **938** | — |
| Positive reviews | 86.1% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 3 months** | Every 23 months |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 223 MB | 68 MB |
| Requires iOS | **8.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [HORIS INTERNATIONAL LIMITED](https://appshunter.io/developer/646324304) | [Iker Vazquez](https://appshunter.io/developer/1032978250) |

## What reviewers say

### Euclidea

[App page](https://appshunter.io/ios/app/euclidea/id927914361)

Engage in geometric construction puzzles based on Euclidean principles. Solve increasingly difficult challenges using innovative tools, with options to explore, get hints, and compete with friends. Unlock new levels by earning stars or purchase an in-app item to remove restrictions.

**Highlights:** 156 geometric puzzle levels, 10 innovative construction tools, Explore mode with hints, Dynamic drag, zoom, and pan interface, Game Center competition, Unlockable tools and shortcuts

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

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock the Rest Levels | $0.99 | one-time |
| Unlock the Rest Hints | $0.99 | one-time |
| Thanks to developers | $0.99 | one-time |
| Night Mode | $0.99 | one-time |
| Many thanks to developers | $4.99 | one-time |
| Many, many thanks to developers | $49.99 | one-time |

**What reviewers like**

- 🚀 Excellent interface
- 🚀 Smooth controls
- 👍 Challenging and engaging puzzles
- 👍 Helps learn and improve geometry skills
- 👍 No ads or in-app purchases

**What reviewers complain about**

- 🐛 App crashes on launch for some users
- 🐛 Circle tool not snapping to points properly
- 🐛 Solutions not always accepted even when correct
- 🔒 Locked levels require in-app purchases to access

**Reported bugs**

- App crashing on launch
- Circle tool not snapping to points
- Solutions not being accepted correctly

**Requested features**

- Offline mode support
- Ability to mark points on free draw
- Protractor feature
- More supplemental educational content
- Ability to see when multiple solutions exist


### 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 |


## Frequently asked questions

### Is Euclidea free?

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

### Is Even or odd Mental calculation free?

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

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

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

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

Euclidea ships an update every 3 months, and Even or odd Mental calculation every 23 months. Most recently, Euclidea was updated on October 29, 2026 and Even or odd Mental calculation on October 20, 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.*