I used to use that one too, but you're supposed to put the 3 numerical digits of your postal code followed by 00. (I have no idea how you're supposed to know that though.)

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OJFord 4 days ago | parent [-]

Really? Or does that just work because it's numbers? I can't imagine how that's useful because without the letters the same 12300 could be in Vancouver or Montreal couldn't it?

	▲	s3graham 3 days ago \| parent [-]
		I don't know much about credit card validation, but I have the impression that the zipcode is just one more correlation that tells them you're more likely to be the real owner of the card. If the 3 numbers I type match the 3 digits of the owner's postal code, it's probably a reasonable signal that I'm the owner (even without the letters).