Credit card numbers are not random. They can be checked by a mathematical formula for validity. Each kind of credit card uses a slightly different rule. For details, see the source code in FormChek.js.

This sample form checks credit cards for validity, so you must enter a valid credit card number. Use one of the sample numbers from this list:

Credit Card	Sample Number
Visa	4111 1111 1111 1111
MasterCard	5500 0000 0000 0004
American Express	3400 0000 0000 009
Diner's Club	3000 0000 0000 04
Carte Blanche	3000 0000 0000 04
Discover	6011 0000 0000 0004
en Route	2014 0000 0000 009
JCB	3088 0000 0000 0009