[spiesd]

I'm interested in the general thrust, but this article is sloppy at best.

> Check digit: The final digit is essentially used to validate the prior 14 digits with an algorithm. Similar digits exist in other types of identifier codes, such as the Universal Product Code (UPC) and the International Standard Book Number (ISBN). The algorithm that the mobile industry uses, the Luhn algorithm, is also used for social security numbers and credit card numbers.

No, just no. SSNs (in the US) don't have check digits.

Also:

> Then there are network identifier numbers—the MAC address bestowed upon you by your WiFi network or mobile provider

Huh? This nonsense ("bestowed upon") serves only to confuse. This is bad tech journalism: it fails to inform the masses, and is transparently worthless to experts.

[toxik]

Many non-American SSN systems do have check digits.

[cesarb]

The Brazilian CPF (our equivalent to the SSN) goes up to eleven (literally) by including not one, but two check digits; IIRC, the first one (the tenth digit) is computed over the first nine digits, and the second one (the eleventh digit) is computed over the first ten digits.

[dhosek]

The geographic aspect of SSNs no longer applies either. My kids have SSNs that start with different digits than my own which was assigned under the old regime where the first digit indicated where the SSN was issued.