Target/Hit: ISBN algorithm

[Lex Systems <lex@LINK.CA>]

At least six people asked me to share the results of my hunt for the
ISBN formula (or algorithm).  The rule is given below, together
with an example that I have added to check it out:

*********************************************************************
(Relayed from Marjorie McPherson)

>    From another list I'm on:
>
>
>    >Does anyone have the formula for calculating the 10th digit (check
>    digit) for
>    >an ISBN from the other 9 digits?
>
>    Multiply the first digit by 10, the second digit by 9, the third
>    digit by 8,
>    the fourth digit by 7, the fifth digit by 6, the sixth digit by 5,
>    the
>    seventh digit by 4, the eighth digit by 3, and the 9th digit by 2.
>    Divide
>    the sum of these products by 11.  Use the remainder as the check
>    digit (if
>    the remainder is 10, use "X").
>
>    Forsan et haec olim meminisse iuvabit.
>    Gary L. Strawn
>    mrsmith@nwu.edu
>    Authorities Librarian, etc.
>    Northwestern University
************************************************************
Jim Again.

This example is from the paperback second edition of the
AACR2 handbook:

0-8389-0301-0

0x10    =        0
8X9     =       72
3X8     =       64
8X7     =       56
9X6     =       54
0X5     =        0
3X4     =       12
0X3     =        0
1X2     =        2
TOTAL   =      220

240/11  =      23 Remainder (Check digit)= 0

It works. I checked the 1987 Canadian World Almanac (paperback) and it
did NOT check out:

0 x 10
-
7 x  9  =63
7 x  8  =56
1 x  7  = 7
5 x  6  =30
-
3 x  5  =15
9 x  4  =36
9 x  3  =27
3 x  2  = 6
2       240  / 11 =  21 Remainder 9

But hey, this is an Almanac, factual accuracy doesn't matter,
right?

Jim Bruce