[CSig] Check Digit and application

[CSig] Check Digit and application

By Andy tsui

Objectives

• Describe check digit

• The need of check digit

• Application in ISBN, Barcode and IDs​

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Pair and share

If you need to enter a long string of number, for example, some credit card number, how can you ensure the number entered is correct?

Check digit

• An extra digit that is calculated from the previous numbers

• To "verify" the numbers are inputted correctly

• Usually check digit is one digit and placed at the end

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Application

• Commonly found in numbers that serves as Identification, e.g.

  • Macau ID, DSEJ ID etc.

  • Credit card number

  • Barcode

  • ISBN

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ISBN

• International standard book number

• An unique "ID" for publication - each edition of book should have assigned an ISBN

• ISBN have two standards:

  • ISBN-10: 10 digit

  • ISBN-13: 13 digit​

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Barcode (for product)

• The last digit of product barcode is also check digit

• To avoid error from barcode scanner​

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Group work

Research online, and draw a poster about calculating check digit in:

1. Barcode (EAN​-13)

2. ISBN-10

3. ISBN-13

4. ​Credit Card (MOD 10)

​Explain the calculating by using examples, step-by-step instruction or flowchart

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