HPlogo HP Data Entry and Forms Management System (VPLUS) Reference Manual: HP 3000 MPE/iX Computer Systems > Appendix D CHECK DIGIT CALCULATION

MODULUS 10

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Modulus 10 calculations detect single transpositions and incorrect keying of a single digit. The calculation is performed as follows:

  • The units position and every alternate position of the basic number is multiplied by 2.

  • The digits resulting from the multiplication are added to those that were not multiplied.

  • The total is subtracted from the next higher number ending with zero. The result is the check digit.

Example

Assume a basic number

9 6 4 3 8

Unit and every alternate

9 4 8

Multiplied by 2

18 8 16

Digits not multiplied

6 3

Add them together

1+8+6+8+3+1+6 = 33

Next higher number ending in zero

40

Subtract sum of digits

-33

Check digit =

7

The base number with check digit

964387

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