Have you ever wondered what the bar code at the bottom of envelopes you receive in the mail means? It gives address information that allows the United States Postal Service to send letters and packages efficiently throughout the country. The three main pieces of a postal bar code include check-sum, framing and number bars. There are short and tall bars that are grouped into various sets of five to represent digits 0 through 9.
Ignore the first and last bar of the bar code. These are the framing bars, and they do not represent address information.
Learn how the digits 0 through 9 are represented in bars. For example, ",||,," represents the number 6. For a list of the numbers and their corresponding bar codes, see the Resources section.
Identify the zip code from the first five sets of five bars on the postal bar code. Remember that five bars of differing sizes represent a certain digit. For example, “l,,l, ll,,, ,l,l, ll,,, ,,,ll” represents the zip code 80501.
Figure out the zip+4 digits in the next four sets of groups of five bars. The zip+4, implemented in 1983, gives more precise information about the location of a certain address within a certain zip code.
Distinguish the last two numbers of the street address by looking at the last two sets of five bars. The last group of five bars is the check-sum digit. According to Microsoft Support, “The checksum is the smallest number that, when added to the total of the other digits, gives a result that is a multiple of 10.”
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