Lehrer Lämpel: Digit Squares app for iPhone and iPad

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.

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