Barcodes: ISBN Numbers
5. ISBN Numbers
ISBN stands for International Standard Book Number and nearly all materials published anywhere in the world are now assigned such a number because of the many advantages in being able to track and identify books by their ISBN number. The ISBN number is a 10-digit number organized into 4 blocks which are separated by hyphens, which are an essential part of the system. The approach used in the ISBN number is that the 4 blocks can vary in size. This approach yields some advantages and some disadvantages. If codes have sections that can vary in length, one needs to have some way of being able to tell where one block ends and the next begins, which increases the length of the number of symbols used in total. Although the ISBN number has 10 information digits, its length is 13 because of the need for the 3 hyphens to separate the blocks. The hyphens could be eliminated if the blocks had specified lengths. (By way of example, the number of partitions of 10 into four nonzero ordered parts where the first part has length 1 or 2 and the last has length 1 is 13.) The first block is a language or country identifier and is partly aimed at giving the language spoken by the target audience for the book. English books for example are assigned a 0 in the first block, while the German language audience uses the code 3 and French the code 2. The code for Malta as a target audience is 99909. The second block is a publisher number, the third block an item number for that publisher, and the last digit is a check digit. Not surprisingly, large publishers have small identification numbers and small publishers have long ones. The pressure of so many publishers and books by publishers is already pushing the limits of this coding system.
10(0) + 9(8) + 8(2) + 7(1) + 6(8) + 5(0) + 4(7) + 3(6) + 2(2) + 1(C).
0 + 72 + 16 + 7 + 48 + 0 + 28 + 18 + 4 + C.
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