# Number 4 Fun vs Brain Duo

The clearest difference is in-app purchases: Number 4 Fun at none against Brain Duo's 2. Brain Duo's advantage is update cadence (every 3 days vs every 70 months) and iOS requirement (13.0 vs 15.6). On price and device support there is nothing between them.

Both are free to download. Brain Duo sells 2 in-app purchases, starting at $3.99 per month. Number 4 Fun asks for nothing beyond the download.

Number 4 Fun ships an update every 70 months, Brain Duo every 3 days. The most recent releases landed on October 26, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Number 4 Fun | Brain Duo |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (3 ratings)](https://appshunter.io/ios/app/brain-duo-brain-training/id6741551111/reviews)** |
| Number of ratings | — | **3** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | — | No |
| Update frequency | Every 70 months | **Every 3 days** |
| Monetization | — | Free with in-app purchases |
| Size | 252 MB | 334 MB |
| Requires iOS | 15.6 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [vmoga](https://appshunter.io/developer/945300832) | [Brain Duo Tech LLC](https://appshunter.io/developer/1794668165) |

## What reviewers say

### Number 4 Fun

[App page](https://appshunter.io/ios/app/number-4-fun/id1482747275)

**Features:** macOS Compatibility

**In-app purchases:** none


### Brain Duo

[App page](https://appshunter.io/ios/app/brain-duo-brain-training/id6741551111)

Engage in fun games designed to enhance focus, concentration, problem-solving, and mental math. Discover more about yourself through personality and IQ tests while fostering personal growth and a sharper mind.

**Highlights:** Personalized brain workouts, Focus and concentration games, Problem-solving challenges, Mental math exercises, Personality and IQ tests, Promotes self-improvement

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full Access - Monthly | $3.99 | per month |
| Lifetime - Premium Access | $19.99 | one-time |


## Frequently asked questions

### Is Number 4 Fun free?

Number 4 Fun is free to download, with no in-app purchases.

### Is Brain Duo free?

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

### Which is updated more often, Number 4 Fun or Brain Duo?

Number 4 Fun ships an update every 70 months, and Brain Duo every 3 days. Most recently, Number 4 Fun was updated on October 26, 2026 and Brain Duo on October 24, 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.*