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unusual facts about Check digit



Checksum

Check digits and parity bits are special cases of checksums, appropriate for small blocks of data (such as Social Security numbers, bank account numbers, computer words, single bytes, etc.

Damm algorithm

The Damm algorithm does not suffer from exceeding the number of 10 possible values, resulting in the need for using a non-digit character (as the X in the 10-digit ISBN check digit scheme).


see also

Verhoeff

Verhoeff algorithm, a check digit algorithm invented by Jacobus Verhoeff