HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

582 AppendixD

CHECK DIGIT CALCULATION

ALPHABETIC CHECK DIGITS

Letters of the alphabet are treated like numbers in either modulus 10 or modulus 11 check

digit calculations. This is done by assigning a digit to each letter of the alphabet as follows:

ABCDEFGHIJKLMN0PQRSTUVWXYZ (=space)

123456789123456789234567890

A value to be checked may be preceded by a plus or minus sign; however, the sign is

ignored in the check digit calculations. To illustrate, perform a modulus 10 check digit

calculation on a value that contains letters as well as numbers:

Assume a basic value 3 4 G 1 2 H

Change the letters to digits 3 4 7 1 2 8

Multiply alternate digits by 2 8 2 16

Digits not multiplied 3 7 2

Sum with digits that were not multiplied 3+8+7+2+2+1+6 = 29

Subtract sum from next higher number ending with zero 30-29 = 1

Check digit = 1

Self-checking number 34G12H1