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I get a warning when enter my client's credit card into my software- it keeps saying "invalid card number". On investigation it turns out that the number is weird, in that it does not satisfy the Luhn Algorithm.

(For those of you who don't know what the Luhn Algorithm is, the number on your credit card is not just random digits, it actually has a particular property, where if you add and multiple various digits together you should get a total divisible by 10. If you don't you can tell the card is invalid. Explanation here.)

Should I try to override this warning? My client swears that their bank says the card is valid.

Should I try to contact their bank on their behalf?

NL - SE listen to your users
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Urbycoz
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1 Answers1

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This sounds like a case of "garbage in, garbage out". Or to put it another way, the problem is between your client's keyboard and his chair.

If the Luhn check is failing, you are entering an incorrect credit card number. Really. Someone has typed it incorrectly, misspelled it, transposed a number, who knows?

Have him send you a photo of the credit card and verify each digit. There's something off.

Rocky
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