# Chaipang Subtraction vs Mars AI

The clearest difference is update cadence: Mars AI at every 2 days against Chaipang Subtraction's every 3 months. Chaipang Subtraction's advantage is iOS requirement (13.0 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Chaipang Subtraction sells 1 one-off in-app purchase and Mars AI sells 7 in-app purchases, starting at $4.99 per 7 days. Whichever you choose, the download price is not the number that matters.

Chaipang Subtraction ships an update every 3 months, Mars AI every 2 days. The most recent releases landed on October 7, 2026 and October 9, 2026 respectively.

## The numbers

| Metric | Chaipang Subtraction | Mars AI |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (4 ratings)](https://appshunter.io/ios/app/mars-ai-study-and-note-taker/id6786825890/reviews)** |
| Number of ratings | — | **4** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 days** |
| Monetization | — | Free with in-app purchases |
| Size | 136 MB | 27 MB |
| Requires iOS | **13.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Wecref Co., Ltd.](https://appshunter.io/developer/1570555584) | [Nexify Labs](https://appshunter.io/developer/1817440343) |

## What reviewers say

### Chaipang Subtraction

[App page](https://appshunter.io/ios/app/chaipang-subtraction/id1614401871)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 차이팡 뺄셈 광고제거 | $2.99 | one-time |


### Mars AI

[App page](https://appshunter.io/ios/app/mars-ai-study-and-note-taker/id6786825890)

This app transforms dense academic material into interactive study missions. It automates organization, generates summaries, flashcards, and practice tests from lectures, PDFs, or links, helping users retain information more effectively and reduce study time.

**Highlights:** Instant AI Summaries, Audio Lecture Podcasts, Gamified Test Prep, Interactive AI Chat, Progress Trackers, Lecture Recording & PDF Upload

**In-app purchases (7)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Mars AI Premium Weekly | $4.99 | per 7 days |
| Mars AI Premium Monthly | $12.99 | per month |
| Mars AI Premium Annual | $49.99 | per year |
| Mars AI Premium Annual | $49.99 | per year |
| Mars AI Premium Annual | $59.99 | per year |
| Mars AI Premium Annual | $69.99 | per year |
| Mars AI Premium Annual | $79.99 | per year |


## Frequently asked questions

### Is Chaipang Subtraction free?

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

### Is Mars AI free?

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

### Do Chaipang Subtraction or Mars AI have ads?

Neither Chaipang Subtraction nor Mars AI shows ads.

### Which is updated more often, Chaipang Subtraction or Mars AI?

Chaipang Subtraction ships an update every 3 months, and Mars AI every 2 days. Most recently, Chaipang Subtraction was updated on October 7, 2026 and Mars AI on October 9, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*