RE: Modulus 10 formula (REPOST)

My recollection is somewhat vague, but there were two basic variations
within all this, being Sum-of-the-digits and Sum-of-the-products.  The
difference is whether you add in calc figure of 12 as 12 or 3.  I forget
which uses what.

Furthermore, in Mod10 I used (Sum-of-the-digits) there are cases where a
transposition error CAN calculate the same check-digit.  (I forget the case,
mebbe 1 outta 100??)  If you keep a FILE of valid numbers, these
keying-combos can be eliminated, thus improving the error ratio.

| -----Original Message-----
| [mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Douglas Handy

| >I guess everyone knows how to break Mod 10 these days, so
| >banks are getting creative in how they apply it.
|
| I think the original intent of Mod10 was simply to provide a
| method of catching
| keying transposition errors using offline devices like card /
| diskette punches,
| as the operator keyed them.
|
| Mod 10 or 11 or LUHN are still helpful with online entry because
| it helps to
| avoid keying transposition errors where they number might
| otherwise actually be
| a valid number but for the wrong account / product.  For example,
| I believe the
| drug industry has used Mod10 for a long time to help reduce the
| chance of the
| wrong (but valid) product code being entered.
|
| The same can be said of many bar code numbers.
|
| Doug