# PrimeXTime vs Serial 7s

The clearest difference is ads: PrimeXTime at none against Serial 7s's shown. PrimeXTime also leads on monetization model (free vs ad-supported). Serial 7s's advantage is iOS requirement (15.0 vs 17.6). On price, rating, ratings volume and update cadence there is nothing between them.

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

On the App Store both sit at effectively the same score — 5.0 for PrimeXTime against 5.0 for Serial 7s. Both are backed by a comparable volume of ratings — 2 and 1 respectively.

PrimeXTime ships an update every 4 months, Serial 7s every 5 months. The most recent releases landed on September 28, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | PrimeXTime | Serial 7s |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (2 ratings)](https://appshunter.io/ios/app/primextime/id1253706544/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/serial-7s/id6480178276/reviews) |
| Number of ratings | **2** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | **Every 4 months** | Every 5 months |
| Monetization | **Free** | Ad-supported |
| Size | 6 MB | 42 MB |
| Requires iOS | 17.6 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 9+ |
| Developer | [Rick Hutchinson](https://appshunter.io/developer/1253697991) | [HFX Lab](https://appshunter.io/developer/1139262927) |

## What reviewers say

### PrimeXTime

[App page](https://appshunter.io/ios/app/primextime/id1253706544)

Engage your mind with a unique number-based puzzle game. Start with a random number and strategically divide by single-digit primes. Bump the number by multiplying by 10 and adding a digit to reach 1 and win.

**Highlights:** Number division by primes, Strategic bumping mechanic, Goal to reduce number to 1, Brain exercise gameplay, Simple, intuitive interface

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

**In-app purchases:** none


### Serial 7s

[App page](https://appshunter.io/ios/app/serial-7s/id6480178276)

This game challenges you to rapidly subtract 7 from a starting number until you can no longer continue. It's based on a cognitive test used to assess attention and memory, with consistent play potentially improving brain skills and helping to prevent cognitive decline.

**Highlights:** Serial 7 subtraction gameplay, Tests attention and memory, Helps prevent cognitive decline, Measures subtraction speed, Randomized starting numbers

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

**In-app purchases:** none


## Frequently asked questions

### Is PrimeXTime free?

PrimeXTime is free to download, with no in-app purchases.

### Is Serial 7s free?

Serial 7s is free to download, with no in-app purchases.

### Which has better reviews, PrimeXTime or Serial 7s?

PrimeXTime and Serial 7s are both rated 5.0 out of 5 on the App Store, from 2 and 1 ratings respectively.

### Do PrimeXTime or Serial 7s have ads?

Serial 7s shows ads; PrimeXTime does not.

### Which is updated more often, PrimeXTime or Serial 7s?

PrimeXTime ships an update every 4 months, and Serial 7s every 5 months. Most recently, PrimeXTime was updated on September 28, 2026 and Serial 7s on October 3, 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.*