# Lehrer Lämpel: Digit Squares — Math puzzles can be fun.

> Math puzzles can be fun. (iPhone/iPad app by Claus Zinn.)

- Source: https://appshunter.io/ios/app/lehrer-lmpel/id948600535 (this page in markdown: same URL + `.md`)
- Developer: [Claus Zinn](https://appshunter.io/developer/889016868)
- Category: Education, Games, Puzzle
- Price: $0.99
- Age rating: 4+
- Requires: iOS 9.3 · 5 MB
- Languages: English, French, German, Italian
- Released: 2015-01-04
- Data updated: 2026-05-17
- User reviews in markdown: https://appshunter.io/ios/app/lehrer-lmpel/id948600535/reviews.md

## What is Lehrer Lämpel?

Digit Squares supports primary school children to practise their skills in basic arithmetic: addition, subtraction, multiplication and division. 

The learner is given a square of nine fields, with some fields already filled with some digits. Each row and column points to its "result number". The task is to fill-out the empty fields ! There are three simple rules:

- all digits from 1-9 must be used to fill the 9 fields.
- no digit can be used twice.
- all sums and products must be correct.

The app is built-upon a state-of-the-art algorithm for diagnosing all student action and for providing targeted, situation-adaptive help.

Pupils can ask Lehrer Lämpel for help at any time. A hint mechanism guides learners towards the next step, or points them to the source of the error.

The app offers the choice between PLUS and PRODUCT puzzles; the first option trains learners' addition and subtraction skills; the second option trains learners' skills in multiplication and division. 

The app supports a large number of randomised exercises (all combinations to place the digits from 0-9 on a playground of 9 fields), and three levels of difficulty.

Optionally, a voice-over is available (male and female voice in English and French; female voice for German) that reads-aloud all help.

Supports English, French and German.

Available on the iPad, for iOS9 or later. 

The app is ad-free. No data is being collected. No web access is required. 

Please consider leaving a review. This helps a lot. Thanks!


## Version history (last 5 releases)

### 1.4 — 2026-05-13

Support for Italian, minor UI improvements.

### 1.3.1 — 2023-02-21

This is a maintenance release.

### 1.3 — 2019-11-19

- Improved feedback (add variation to feedback)
- Minor design improvements

### 1.2 — 2018-12-28

Now gives better feedback to signal correct or incorrect steps, or when square is solved.
Now with system sound to signal square has been solved.

### 1.1 — 2015-11-12

Now also supports iOS9.
Now supports Retina display.
Improved design.

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## More apps by Claus Zinn

- [Lehrer Lämpel: Number Pyramids](https://appshunter.io/ios/app/lehrer-lmpel/id889016865)
- [Lehrer Lämpel: Subtraction](https://appshunter.io/ios/app/lehrer-lmpel/id890390632)
- [Lehrer Lämpel: Addition](https://appshunter.io/ios/app/lehrer-lmpel/id920522698)
- [Lehrer Lämpel: Fractions](https://appshunter.io/ios/app/lehrer-lmpel/id932955952)
- [Lehrer Lämpel: Number Wheels](https://appshunter.io/ios/app/lehrer-lmpel/id959272416)

All apps by Claus Zinn: https://appshunter.io/developer/889016868

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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 2026-05-17.*