A check digit is a digit added to a string of numbers for error detection purposes. Normally, the check digit is computed from the other digits in the string. A check digit helps digital systems detect changes when data is transferred from transmitter to receiver.
The check digit is the decimal equivalent of the binary checksum used in binary systems.
A check digit algorithm calculates a check digit based on an original character string, such as an account number. The receiver recalculates the check digit to verify data entry accuracy. If the recalculated character string contains the correct check digit, the data is error-free and may be used. However, a character string that does not include the correct check digit indicates a transfer error, which signals that data must be re-entered and/or reverified.
When a check digit system is used, error detection and data implementation complexities and compromises are inevitable. Simple check digit systems easily understood by humans cannot detect errors with complete accuracy, unlike complex systems that use more complicated error detection algorithms.
A recommended check digit characteristic is left-padding with zeros, which never alters the original check digit and allows for the application of digits with varied and dynamic length.
Share this Term
Tech moves fast! Stay ahead of the curve with Techopedia!
Join nearly 200,000 subscribers who receive actionable tech insights from Techopedia.
Latest Articles
By: Kishore Jethanandani | Contributor
By: Devin Partida | Editor-in-Chief for ReHack.com
By: Terri Williams | Contributor
By: Rebecca Koehn | Techopedia Editor
