# Thread: Credit card virtual number

1. ## Credit card virtual number

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

2. If you are only talking about digits for the credit card virtual number then it should be 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 = 10 ^ 16

Originally Posted by fractal
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

3. ## 3!

@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.

4. Originally Posted by tester85
If you are only talking about digits for the credit card virtual number then it should be 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 = 10 ^ 16
Agree it. In fact ,i know mastercard cann't be some digital on some position.For example ,i just saw first number of MasterCard is 5 .