system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Social security numbers represent everyone in America with only 9 digits, yet every single account I have - cable, phone, gas, etc. - has at least 12 digits. What purpose do the extra digits serve?
gpt
Ability to parse data specific to a region, segment, type, etc.  Utility for instance might want to segregate commercial from residential, service areas and other business needs.  Having these identifiers in the account number allows data to be sorted quickly and accurately.