# Serial 7s — Serial Sevens Subtraction.

> A game for rapid serial subtraction of seven to test and improve cognitive skills. (iPhone/iPad app by HFX Lab.)

- Source: https://appshunter.io/ios/app/serial-7s/id6480178276 (this page in markdown: same URL + `.md`)
- Developer: [HFX Lab](https://appshunter.io/developer/1139262927)
- Category: Games, Education, Trivia
- Price: Free
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 9+
- Requires: iOS 15.0 · 42 MB
- Languages: Korean, American English
- Released: 2024-04-01
- Data updated: 2026-09-22
- Monetization: ad-supported
- User reviews in markdown: https://appshunter.io/ios/app/serial-7s/id6480178276/reviews.md

## What is Serial 7s?

Serial 7s is a brain training game that tests how fast you can perform continuous subtraction of 7 from a starting number.
Inspired by the classic "Serial 7s" task—a standard component of the Mini-Mental State Examination (MMSE)—this game gives a proven cognitive test a fresh twist.
Starting with a randomly generated number between 99 and 105, your total time to complete 14 consecutive subtractions of 7 is measured.

Serial subtraction by 7 is widely used to evaluate focus, attention span, and working memory. Regular practice can help sharpen your mind and boost cognitive fitness.
Recommended for anyone interested in brain training, keeping their mind active, or supporting long-term cognitive health and dementia prevention.

## Key features

- Serial 7 subtraction gameplay
- Tests attention and memory
- Helps prevent cognitive decline
- Measures subtraction speed
- Randomized starting numbers


## Frequently asked questions about Serial 7s

### What is Serial 7?

Serial 7 is a game designed to test and improve your ability to subtract the number seven consecutively from a starting number. It's based on a cognitive test used to assess attention and memory.

### How does Serial 7 help with brain health?

Consistent play of Serial 7 can help improve brain skills such as attention and memory. It is also recommended for users interested in dementia prevention and maintaining cognitive function.

### What is the gameplay like in Serial 7?

The game randomly selects a starting number between 94 and 100. You then measure how quickly you can subtract 7 in a row until you can no longer continue the sequence.

### Is Serial 7 free to play?

Yes, Serial 7 is free to download and play. However, it does contain advertisements.

### Does Serial 7 have ads?

Yes, Serial 7 contains advertisements.

### What devices is Serial 7 available on?

Serial 7 is available on iPhone, iPad, and iPod devices.

### What is the age rating for Serial 7?

Serial 7 has an age rating of 9+.

### How often is Serial 7 updated?

The latest version of Serial 7 is 1.0.3, and it was last updated on August 20, 2024.

## Version history (last 4 releases)

### 1.1.0 — 2026-09-21

Game modes updated to 2 options.
Added 'Remove Ads' in-app purchase.

### 1.0.3 — 2024-08-20

Improved the performance.

### 1.0.1 — 2024-04-05

- Added a daily notification feature.

### 1.0.0 — 2024-04-01

No release notes.

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## More apps by HFX Lab

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All apps by HFX Lab: https://appshunter.io/developer/1139262927

## Related topics

[hfx lab](https://appshunter.io/ios/topics/hfx-lab)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-22.*