Chapter 8
Number Theory

Applet 10. Check Digit Calculator
 
A calculator to verify the check digits of UPC and ISBN numbers.

Start...

  1. Select the type of code you want from the tabs at the top of the calculator.
  2. Enter the code number into the "Code" field.
  3. When you press "Enter" or click on the "OK" button (the green check), the window below will show the check digit and confirm whether the code is valid or not.