16.1 Bank Checks and Codabar - Video

Key Ideas

  • A variation of UPC uses a similar sum with weights 2 (odd positions) and 1 (even positions). This codabar scheme is used for credit cards. Specifically, the Luhn algorithm takes the sum and adds the number of digits in odd positions that exceed 4; the resulting number must end in 0 to be a valid code.
  • Bank check scheme 7a1+3a2+9a3+7a4+3a5 +9a67a7+3a8. The last digit of the sum is used as the check digit a9.