Can you remember any of the numbers without looking at the card?
Chances are if you could not remember all of them, you either remembered the first few numbers or the last few.
I think most people have seen the privacy technique of masking out a social security number or credit card number by hiding digits with an “X”, like XXX-XX-1111. Here is an interesting phishing site we encountered that tries to convey a false sense of privacy and security by hiding credit card digits to make the user trust the site that really is phishing for personal information.
Did you know that the first digit in your credit-card number signifies the system:
Travel/entertainment cards (such as American Express and Diners Club)
As you can see, this site targets Visa card holders.
Someone who casually accesses the site and isn’t paying attention might be fooled into thinking that the site is legitimate should they have a Visa card.
According to 2006 data, 44% of all credit cards issued would start with a "4" as Visa held a 44% market share.