[Rygian]

There are card numbers that don't satisfy Luhn.

[drdaeman]

I'm really curious now - which cards don't conform?

I always thought it's basically an industry standard and no network issues cards that don't have a correct checksum.

[ceejayoz]

https://stackoverflow.com/questions/7863058/does-the-luhn-al... has a list.

[drdaeman]

Wow, thank you. TIL!

[exikyut]

TIL, although this isn't a field I need perfect knowledge of.

I wonder if people with such cards have inexplicable problems with certain payment systems?

Edit: just saw the sibling comment, was viewing an old copy of the page