# GCD LCM Calculation vs Prime Rush

The clearest difference is in-app purchases: GCD LCM Calculation at none against Prime Rush's 1. GCD LCM Calculation also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17). Prime Rush's advantage is update cadence (every 3 weeks vs every 2 months). On price and ads there is nothing between them.

Both are free to download. Prime Rush sells 1 one-off in-app purchase. GCD LCM Calculation asks for nothing beyond the download.

GCD LCM Calculation ships an update every 2 months, Prime Rush every 3 weeks. The most recent releases landed on November 8, 2026 and November 9, 2026 respectively.

## The numbers

| Metric | GCD LCM Calculation | Prime Rush |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | Yes | Yes |
| Update frequency | Every 2 months | **Every 3 weeks** |
| Size | 14 MB | 21 MB |
| Requires iOS | **15.0** | 17 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Kazuhisa Kobayashi](https://appshunter.io/developer/1580882000) | [Ayumu Izumi](https://appshunter.io/developer/1822273057) |

## What reviewers say

### GCD LCM Calculation

[App page](https://appshunter.io/ios/app/gcd-lcm-calculation/id6621190448)

**Features:** macOS Compatibility

**In-app purchases:** none


### Prime Rush

[App page](https://appshunter.io/ios/app/prime-rush-math-time-attack/id6755986782)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Plan | $1.99 | one-time |


## Frequently asked questions

### Is GCD LCM Calculation free?

GCD LCM Calculation is free to download, with no in-app purchases.

### Is Prime Rush free?

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

### Do GCD LCM Calculation or Prime Rush have ads?

Both GCD LCM Calculation and Prime Rush show ads.

### Which is updated more often, GCD LCM Calculation or Prime Rush?

GCD LCM Calculation ships an update every 2 months, and Prime Rush every 3 weeks. Most recently, GCD LCM Calculation was updated on November 8, 2026 and Prime Rush on November 9, 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.*