2.2 · Lesson 4 of 5
Check digits
Syllabus 2.2.4
What this lesson covers
- Explain how check digits detect data entry errors
Key vocabulary
- Check digit
- A digit calculated from the other digits in a number and added to the end, to catch data entry errors.
- Data entry error
- A mistake made when a number is typed or scanned in, such as a wrong digit or two digits swapped.
- Modulo 10
- The algorithm used for barcode check digits: weight, add, find the remainder after dividing by 10, subtract from 10.
- Weight
- The number each digit is multiplied by. For barcodes, 1 and 3 alternately.
- Barcode
- A pattern of bars that represents a number, where the last digit is the check digit.
- ISBN
- The number that identifies a book. Its last digit is a check digit.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 6 terms
- Activity 1: Check digits · 6 questions
- Activity 2: Check digits quiz · 8 questions
- Activity 3: Using a check digit · drag and drop