How ISBN Checksum works
Posted: Sun Nov 30, 2003 12:05 pmhttp://www.morovia.com/education/symbology/isbn.asp
An ISBN number consists of 9 digits, followed by a checksum, which is a digit from 0 to 9, or an X. There may be dashes among the digits at seemingly random places.
The checksum is calculated as follows:
The first 9 digits are multiplied by their position, and these numbers are summed up. Ie, the sum is first digit * 1 + second digit * 2 + ... + 9th digit * 9
The remainder mod 11 is used as the checksum (X is used to represent 10).
A web utility can be found on Morovia web site: http://www.morovia.com/education/utilit ... n.asp#ISBN
An ISBN number consists of 9 digits, followed by a checksum, which is a digit from 0 to 9, or an X. There may be dashes among the digits at seemingly random places.
The checksum is calculated as follows:
The first 9 digits are multiplied by their position, and these numbers are summed up. Ie, the sum is first digit * 1 + second digit * 2 + ... + 9th digit * 9
The remainder mod 11 is used as the checksum (X is used to represent 10).
A web utility can be found on Morovia web site: http://www.morovia.com/education/utilit ... n.asp#ISBN