If by "fake" you mean ones that pass number validation on web sites, that's easy. I wrote python code to check and generate valid numbers back in the '90s; it's a simple, well known check digit algorithm appended at the end. https://en.wikipedia.org/wiki/Luhn_algorithm.
If by "fake" you mean ones that pass number validation on web sites, that's easy. I wrote python code to check and generate valid numbers back in the '90s; it's a simple, well known check digit algorithm appended at the end. https://en.wikipedia.org/wiki/Luhn_algorithm.