Several retailers have gotten together and begun issuing a “state” credit card that is good only in stores in their state. As a courtesy, salesclerks are permitted to transcribe the 15-digit account number by hand (after getting it from the accounting office) if the customer is not carrying the card. The only problem with accounts that retailers have noticed so far is that sometimes erroneous account numbers are accepted into the computer system, resulting in a bill being issued to a nonexistent account.
a. What sort of validity test would clear up the problem? How? Respond in a paragraph.
b. Suggest an alternative data entry method that might alleviate this problem altogether.