# UPC Barcode

Almost every single product you buy has a UPC barcode printed somewhere on it. UPC stands for Universal Product Code and it is used by companies to help keep track of inventory. UPC bar codes were originally designhed to aid grocery stores in speeding up the checkout process. Eventually the barcode system spread to other indstries and now the UPC system is managed by the Uniform Code Council (UCC).

Example of a UPC barcode.

UPC codes consist of a black and white barcode that is scannable by machines and a 12 numbers. The first six digits of a UPC bar code represent the manufacturer identification number. These numbers are the same for all products manufactured by a particular company. The next five digits represent the specific item number. These will vary depending on the specific manufactured product. The final digit is called the check digit. This number is used by the scanner to determine if the barcode was scanned correctly.

The process for calculating the check digit for a standard 12 digit barcode is as follows:

- Add the value of all the digits in an odd position and multiply that number by three.
- Add the calue of all the digits in an even position to the result of the first calculation.
- Find the remainder of that result when it is divided by 10.
- Subtract that result from then unless it is zero to get the check digit.