How Do UPC Codes Work?

Have you ever wondered what that numbered zebra stripe on the box of every purchase really means? Yes, your fears are true. It does contain secret messages the manufacturer is trying to communicate to the bar code scanner. But we have a secret decoder ring you can use to figure them out using your brain powers.

So let’s take a look at the sets of numbers found on a every UPC bar code. The numbers mean the same thing as the lines, but those aren’t very user-friendly for humans. Here’s what the different numbers mean:

1st: Product category.
2-6: Manufacturer ID.
7-9: Family code – delineates the specific product, including size.
10-11: Value code – establishes any applicable coupons.
7-11: Together the family and value code form the Item Number. It is assigned by the manufacturer’s UPC code coordinator who is in charge of keeping all the UPC numbers straight and unique.
12: Check digit – a “check sum” that makes sure all the previous numbers were read correctly. It’s computed based on a formula involving all the previous numbers. This formula is called the “Mod10Method” or “Luhn algorithm” and it works like this:

1. Working from right to left, assign the first number on the right as odd, the second as even, the third as odd, etc.
2. Add up all the odd digits and multiply by 3.
3. Add up all the even digits.
4. Add up the results of 2 and 3.
5. Divide that by 10. The check digit is the number that when added to the remainder equals 10.

So now when we have to get bar codes on the back of our necks, you’ll be able to look at your friend’s and tell which fertilization plant he came from.

Learn what bar code numbers mean in the wake of major cereal recall [The Hot Word]
Universal Product Code [Wikipedia]

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