Integers with leading zeroes

[Gregory Ewing]

Michael Torrie wrote:
> A credit card number is indeed a number, and there are
> mathematical formulas for determining if a particular number is a valid
> (as in well-formed) credit card number,

If you're talking about the check-digit algorithm,
that doesn't treat the whole number as an integer,
it works on the individual digits:

http://www.datagenetics.com/blog/july42013/

> and possibly to identify what kind of card it is.

That's determined by the leading digits, and can
be done just as well by treating them as characters.

-- 
Greg