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Old 29th Oct 2017, 11:59
  #66 (permalink)  
sandozer
 
Join Date: May 2007
Location: Dunfermline
Posts: 128
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I just know you will be transfixed and amazed as to how they got the last checksum letter on your service number, someone posted this a while back, sorry can`t remember who. Works on BE service numbers, not sure of others.


Multiply the first digit by 8
second by 17
third by 4
forth by 16
fifth by 2
sixth by 13
seventh by 5
Add these up to produce answer A

Divide A by 23

Chop all the decimal places then multiply by 23. The result is answer B.

Subtract B from A to produce answer C which is a letter of the alphabet where Zero = A, 1 = B, 2 = C etc. But omit "O" and "I" to avoid confusion with "0" and "1".

A slight change to the algorithm fixes it. Multiply the last digit by 1 (not 5), discard "I" and "O" in the alphabet and start at zero when counting through.

I was 48th entry St Athan, and it gives me the correct check letter. 1948...N
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