|A check digit is a redundancy check used for error detection. It consists of a single digit computed from other digits in the message. When a barcode is scanned, the check digit is computed with a standardized algorithm using various operations on the other digits. The computed check digit is then compared to the check digit value explicitly encoded in the trailing end of the bars. If the values are equal, the scan is assumed to be successful, otherwise an error was detected resulting in a failed scan.
Note: This demo will not work with 8-digit truncated barcodes or with any non-American standard barcodes.