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Figure This!

The ZIP in ZIP Code stands for Zone Improvement Plan.

The bar-code system used by the US Postal Service is called Postnet.

The bar code found on most supermarket items is a UPC type A. Such codes consist of 12 digits. When space does not allow 12 digits, a UPC type E code—which is only 8 digits—is used.

The US grocery industry formally adopted the UPC system in 1973.

The mission of the Uniform Code Council, based in Dayton, Ohio, is to take a global leadership role in establishing and promoting multi-industry standards for product identification and related electronic communication.

Bar codes are also used by libraries, airlines, and blood banks.

After the ZIP Code bars, the next two groups of five bars represent the delivery code for the mail on the primary street address. The last set of bars in the code represents a check digit that helps a computer determine if the first digits have been read correctly. The check digit at the end of a US Postal Service code is calculated by adding the 11 previous digits in the the code, then identifying the smallest digit that can be added to this sum to obtain a multiple of 10. For example, the check digit for the postal code in the Challenge is 3, since:

5 + 9 + 8 + 0 + 1 + 2 + 7 +
1 + 7 + 3 + 4 = 47

and the smallest positive number that can be added to 47 to produce a multiple of 10 is 3.

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