alt Hacker NewsThat doesn't seem to be more than an order of magnitude off between available numbers and issued cards - a cursory search says there are over a billion credit cards in circulation in the US alone.
That doesn't seem to be more than an order of magnitude off between available numbers and issued cards - a cursory search says there are over a billion credit cards in circulation in the US alone.
I think you're confusing the available number space per BIN (often used for a single card product) with the number of available numbers per network.
Visa and Mastercard each have 14 digits worth of permutations to play with, excluding the first and last digits. That's one hundred trillion numbers.
Assuming 8 billion people in the world, each person can hold 12,500 of either Visa or Mastercard before a collision happens. (As above, the number space is smaller because of how BINs are issued, but that's still plenty.)