# Forexamplewithisbn 013139139thefinaldigitwouldbe 0

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Unformatted text preview: ontrol. One Possible Approach ‐ Checksum "Modulus 10" Consider a simple scheme in which the first nine digits are simply added up and the sum (or rather the 'ones' digit in the sum) is used as the final ISBN digit. For example with ISBN 0‐13‐139139‐_, the final digit would be '0': ISBN 0 1 3 1 3 9 1 3 9 0 sum 0 + 1 + 3 + 1 + 3 + 9 + 1 + 3 + 9 = 30 If any single digit is written incorrectly, this scheme will detect that error; however, if two digits are switched with each other, the sum will not be affected, and that error would go undetected. Although this simple 'checksum' does provide some error detection, it is not good enough for this application. • • CNT 3004 ‐ Polynomials Error Detection Method ISBN 0‐13‐139139‐9 ISBN 0 1 3 1 3 9 1 3 9 0 sum 0 + 1 + 3 + 1 + 3 + 9 + 1 + 3 + 9 = 30 Modulus Arithmetic Note that taking only the last digit in a decimal number is equivalent to dividing the number by 10 and using only the remainder. This result is also referred to the sum "modulus 10". This is generally written as: 30...
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## This note was uploaded on 10/05/2010 for the course CNT CNT 3004 taught by Professor K during the Spring '10 term at University of Central Florida.

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