Checking for Errors

Remember the two most common types of data entry errors: a single-digit error and a transposition error.

One method of identifying data entry errors is through a check digit – a digit appended to the end of the identification number for the purpose of detecting single-digit, transposition, and other types of errors. A check digit is standard for identification numbers such as airplane ticket numbers, ISBNs, UPC barcodes, credit card numbers, checking account numbers, passport numbers, VINs (vehicle identification numbers), POSTNet codes (bar codes from mailing addresses), etc. Older identification numbers such as social security numbers do not have a check digit.

Close up image of the check digit number in a UPC bar code.