ISBN Codes
Contents
ISBN
ISBN: International Standard Book Number
10-digit ISBN
The first 9 bits correspond to the country group, publisher and title. The last bit is used as a check-bit with a character from /[0-9X]/
(sum i * xi from 1 to 10) = 0
separate x_10 10 mod 11 === -1 mod 11
x_10 = (sum i * xi from 1 to 9) % 11