"simply enter your card number" It's horribly wrong to even suggest that. The instructions should say "type 4111.... I don't want your credit card number", and

"simply enter your card number" It's horribly wrong to even suggest that. The instructions should say "type 4111.... I don't want your credit card number", and should pop up an error if a valid checksummed card number is entered. Don't miss an opportunity to help people lean safe habits.