Breakdown of a UPC (Universal Product Code):
- lone "0" on the bottom left means it's for a regular grocery item - a "2" is for items sold by weight (meat, produce, etc.); a "3" is for drugs, and a "5" identifies a discount coupon
- the first 5 digit cluster identifies the manufacturer; i.e. Procter & Gamble's is 37000 and Colgate-Palmolive's is 35000
- the tall center bar signals the upcoming 5-digit product code
- the next 5 digit cluster represents the product code - they aren't unique (it's combination with the manufacturer code does) - it encodes information about a product's brand, size, flavor, etc.
- the last digit on the bottom right is the check digit - if all the other numbers are run through a verification formula it's the number you end up with - it detects bar code shavvy shopper's tampering to lower the price
