ISBN (International Standard Book Number)
is a unique number assigned to each book.
ISBN-13:
• The number has 12 information digits and ends with 1 check
digit.
• Assuming the digits are "abcdefghijkl-m" where m is the check digit. Then
the check digit is computed by the following formula:
m = ( [a b c d e f g h i j k l] * [1 3 1 3 1 3 1 3 1 3 1 3] ) mod 10