Bar Codes in Action
Bar codes incorporate high-tech number generation and tracking.
The bar code, invented in the 1940s by Ben Silver and John Woodland, is a series of numbers and dashes. The dashes are read by a machine. The 12-digit number can be read by people.
Bar codes have a UPC number. UPC stands for Universal Product Code. Product makers apply to the Uniform Code Council for permission to get a UPC number, which requires an annual fee. The UCC then assigns a six-digit number to each manufacturer.
The next five numbers in the 12-digit bar code correspond to a particular item. Even different sizes of the same product (a 12-ounce can of vegetables versus a 16-ounce can of the same vegetables) have unique bar codes.
The last digit is a "check digit," which prompts the scanning machine to run a "check" to see that the item was scanned correctly. If the scan returns a different number from the one assigned to the item, then the scanner returns a negative scan and human intervention is required.
To find the "check digit" in a 12-digit UPC bar code, do the following:
For example, take the number 111111111111.
So, f, the check digit is 7.
The machine reader doesn't need the numerals, though. It scans the space between the bars in order to get the code.