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Adding and subtracting decimals

This page was translated from German with AI. It has not been checked by a native speaker. Original page in German

Bread 2,45 € and milk 3,80 €: what does it all cost together? You calculate in writing, comma under comma.
📄 Open worksheet (PDF, German)

The video

In the video the calculation is done in a squared exercise book, digit by digit.

Subtitles are available in ten languages. Choose them at the bottom right of the video.

Contents of the video

  1. 0:00 Introduction
  2. 0:20 Comma under comma
  3. 0:41 Adding
  4. 1:04 Different lengths
  5. 1:39 Subtracting
  6. 2:17 Careful, mistake!
  7. 2:40 Try it yourself

The most important points

Comma under comma (Komma unter Komma)

Write the numbers below each other by place value: comma under comma, ones under ones, tenths under tenths. Calculate as with whole numbers. The comma in the result is in the same place.

2{,}45 + 3{,}80 = 6{,}25.
\(2{,}45 + 3{,}80 = 6{,}25\).

If the numbers have a different number of places, fill up with zeros: \(12{,}7 + 0{,}365 = 12{,}700 + 0{,}365 = 13{,}065\).

Filled up with zeros.
Filled up with zeros.
5{,}00 - 2{,}35 = 2{,}65.
\(5{,}00 - 2{,}35 = 2{,}65\).

The worksheet

Here you can see the worksheet for the video (in German). First it explains everything again, then there are practice tasks at three levels. You can also open it as a PDF and print it.

📄 Open worksheet (PDF, German)

The worksheet – Page 1
Page 1/4
The worksheet – Page 2
Page 2/4
The worksheet – Page 3
Page 3/4
Show the worksheet solutions
The worksheet – Page 4
Page 4/4

Try it yourself

Task

Calculate in writing: a) \(4{,}7 + 2{,}56\) b) \(8 - 3{,}4\)

Show solution

a) \(4{,}70 + 2{,}56 = 7{,}26\) b) \(8{,}0 - 3{,}4 = 4{,}6\)

Keep learning with a language model

Du bist meine Mathe-Lehrkraft. Ich lerne Deutsch als Zweitsprache. Unser Thema: Dezimalbrüche schriftlich addieren und subtrahieren (Komma unter Komma, mit Nullen auffüllen). Stelle mir nacheinander fünf kurze Aufgaben. Warte immer auf meine Antwort. Sag mir dann, ob sie richtig ist, und erkläre kurz, warum. Benutze einfache deutsche Sätze.

How this was made: The idea, structure and examples of the series are mine. I made them with the help of AI: a language model (LLM) built the slides of the video following my instructions. The voice was generated with Qwen3-TTS, modelled on my own voice.

The subtitles, the translations, the worksheet and this page were also made with the help of AI. The translations have not been checked by native speakers.

The videos, worksheets, texts and prompts in this series are licensed under CC BY 4.0: you may use, change and share them if you name the source.