If the first 6 digits make up the issuer, since there are only 10 remaining digits, wouldn't that mean there are only 10^10 numbers per issuer? Where's the othe

If the first 6 digits make up the issuer, since there are only 10 remaining digits, wouldn't that mean there are only 10^10 numbers per issuer? Where's the other factor of 100 coming from (IIRC, OP said there were 10^12)? > My guess is the credit card itself as a concept will be long gone before the numbers are all used up. I agree. Products like "privacy.com" hint that we could be approaching a "new number per purchase" meta. Even in that edge-case, if one million issuers get to have 10 billion numbers each, that would leave tens of concurrent purchases per person per issuer for an issuer with a billion users. A monopoly-level media site that lets you open a paid-subscription to multiple people could easily end up needing tens of concurrent cards per user. It seems like issuer-to-issuer number recycling would be required for sure.