Several retailers have gotten together and begun issuing a “state” credit card that is good only in stores in their state. As a courtesy, sales clerks 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.

a. A test for invalid values will help to solve this problem. Include a check-digit on the number.

b. An alternative method would be to have a lookup screen that would allow the user to enter a name and look up the number. Perhaps a G U I screen with a drop-down list would be useful in this situation, although the list of numbers would be extensive. Have the accounting office transfer the number directly into the retail cash register.