The other day, my brother & I were online shopping and to pay the merchant, we used a credit card virtual number from our credit card company website. It's mastercard virtual number cc generator if you're curious. Anyways, how many unique, non-identical, 16-digit number from 0 to 9 that can be generated? I wonder how long because it would run out of number, similarly with phone number in the US where it is just 10-digit. Thanks, newbie
@tester85: Are you saying that there can be a maximum of 10^16 credit card number that exists with the mastercard 16-digit? I'll try to clarify here. So there are 16 place holder, where each one can be occupied by any number from 0 to 9. how many combination can be made? For example, ABC can be sorted six times without repetition. ABC ACB BAC BCA CAB CBA which is like 3!=6. Is there something similar for the credit card question. Thanks.