5. Check Digit
This is used when you want to be sure that a range of numbers has been entered correctly for example a barcode or an ISBN number:
ISBN 1 84146 201 2
The check digit is the final number in the sequence, so in this example it is the final ‘2’.
The computer will perform a complex calculation on all of the numbers and then compare the answer to the check digit. If both match, it means the data was entered correctly.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Using a check digit in barcode
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