Developed by Dr Claus Zinn

Computer Scientist and Educational Researcher

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Lehrer Lämpel

Version 1.0
Lehrer Lämpel: Long Multiplication

An educational app that supports primary school kids to train their long multiplication skills.
  • Practising long multiplication
  • Supports multiplication of integer and decimal numbers
  • Various levels of difficulty
  • Worksheet with many different multiplication tasks
  • Unlimited number of (randomised) exercises
  • Support for self-defined multiplication tasks
  • Direct feedback for correct/incorrect steps
  • Intelligent next-step help and error correction
  • Multi-lingual help page (English, German, French)
  • Available for iPad tablets, from iOS8
  • Price: 0.99 USD, 1.09 Euro
Compatible with the iPad. Requires iOS7 or later. No WiFi, Edge, or 3G network connection required. No ads.


Lehrer Lämpel is an educational app that supports primary school children (usally 3rd or 4th grade) to practise their long multiplication skills.

Simple input method to add digits to the blackboard.

Immediate feedback option where incorrect steps are immediately marked red and where correct steps are immediately marked green.

Pupils can ask Lehrer Lämpel for help at any time. Help first removes an erroneously learner step; if there are no errors, a single step is performed towards the solution.

All teacher steps towards the solution are followed-up with a step explanation as well.

Various degrees of difficulty

Supports self-defined long multiplication tasks and there is a work-sheet, and randomised exercises

Supports English, French and German.

Available on the iPad, for iOS7 or later.


Version 1.0

Released on November 2nd, 2016
  • Initial Release.


Privacy Policy

Our privacy policy is rather simple. We do not collect any information from you and your child when using our app or browsing our website.

You or your child will never be prompted to provide any sort of information in our app. You are free to use the contact form on the website to give us your feedback, ask questions, elicit new app features, or file a bug report. For this, you can equally contact us at

We will use your contact information only for being able to reply to your requests. It will not be shared with anybody else.

Our app is solely financed by its price tag, there are no in-app purchases, and the app is ads-free.


Contact Us

Please use the following form for questions, feedback, feature requests etc.

Our email:

Postal Address

Dr. Claus Zinn, Diplom-Informatiker (Univ.)
In der Gebhardsoesch 33
78467 Konstanz, Germany