ISBN-13

I don't know how many of you aware of ISBN-13 check digit.
In order to accommodate the growing number of books being published each year, beginning January 1, 2007, all 10-digit International Standard Book Numbers (ISBNs) will be converted to new 13-digit ISBNs. ISBN 13 (in use January, 2007) is equal to the EAN-13 code (European Article Number) found underneath a book's barcode. It can be used for error detection, the decimal equivalent of a binary checksum.
The Manual calculation of an ISBN-13 check digit begins with the first 12 digits of the thirteen-digit ISBN (thus excluding the check digit itself). Each digit, from left to right, is alternately multiplied by 1 or 3, then those products are summed modulo 10 to give a value ranging from 0 to 9. Subtracted from 10, that leaves a result from 1 to 10. A zero (0) replaces a ten (10), so, in all cases, a single check digit results. For example,
the ISBN-13 check digit of 978-0-11-322799- is calculated as follows
s = 9×1 + 7×3 + 8×1 + 0×3 + 1×1 + 1×3 + 3×1 + 2×3 + 2×1 + 7×3 + 9×1 + 9×3 = 9 + 21 + 8 + 0 + 1 + 3 + 3 + 6 + 2 + 21 + 9 + 27 = 110 110 / 10 = 11 remainder 0 10 – 0 = 0 Thus, the check digit is 0, and the complete sequence is ISBN 978-0-11-322799-0.
Bowker is excited to introduce the new 13-digit. You can also convert Ten digit numbers to Thirteen digit numbers with the following link http://www.isbn.org/converterpub.asp