# Subtraction Math vs ČRS

The clearest difference is price: ČRS at Free against Subtraction Math's $1.99. Subtraction Math's advantage is ads (none vs shown) and device support (5 vs 3). On update cadence, in-app purchases and iOS requirement there is nothing between them.

ČRS is free to download; Subtraction Math costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Subtraction Math ships an update every 4 months, ČRS every 2 months. The most recent releases landed on September 22, 2026 and October 4, 2026 respectively.

## The numbers

| Metric | Subtraction Math | ČRS |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | **[3.9 (7 ratings)](https://appshunter.io/ios/app/subtraction-math-ibbleobble/id978343612/reviews)** | — |
| Number of ratings | **7** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 4 months | **Every 2 months** |
| Monetization | Paid | — |
| Size | 17 MB | 21 MB |
| Requires iOS | 15.0 | 15.0 |
| Devices | **iPhone, iPad, iPod, Mac, Apple TV** | iPhone, iPad, iPod |
| Age rating | 4+ | 12+ |
| Developer | [KidDotCo](https://appshunter.io/developer/819246599) | [Trilobite Technologies, s.r.o.](https://appshunter.io/developer/1106306899) |

## What reviewers say

### Subtraction Math

[App page](https://appshunter.io/ios/app/subtraction-math-ibbleobble/id978343612)

This educational game helps children aged 5-8 practice subtraction skills through engaging drills and multiple-choice questions. It offers a flexible learning pace with an optional timer and vibrant visuals to make arithmetic fun.

**Highlights:** Subtraction drills, Multiple choice format, Adjustable difficulty, Optional timer, Colorful graphics and sounds, Universal purchase

**Features:** iMessage stickers

**In-app purchases:** none


### ČRS

[App page](https://appshunter.io/ios/app/crs/id6748644426)

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

**In-app purchases:** none


## Frequently asked questions

### Is Subtraction Math free?

Subtraction Math costs $1.99, with no in-app purchases.

### Is ČRS free?

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

### Do Subtraction Math or ČRS have ads?

ČRS shows ads; Subtraction Math does not.

### Which is updated more often, Subtraction Math or ČRS?

Subtraction Math ships an update every 4 months, and ČRS every 2 months. Most recently, Subtraction Math was updated on September 22, 2026 and ČRS on October 4, 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.*