How to Determine the Check Digit in a UPC Code

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Food consultants often advise new entrepreneurs in the food industry to register for at least two to three codes for their product. Retailers and Wholesalers usually require you to have one to sell your product in their stores. It is because UPCs make checking inventory, processing sales, and paying you much easier for them. UPCs come with a 12 digit code pertaining of a 6 digit manufacturer code in the first few digits, a 5 digit item code after that and a check digit code at the end to ensure that the item was scanned correctly.

The check digit formula is a little bit complicated, but can be understood with a little bit of analysis. The check code first adds up all the digits in odd positions in the numerical order (the first, third, fifth, and so on), and then multiplies that number by three. It then adds all the digits together that is in the even spots in the numerical order (the second, fourth, sixth, and so on). This sum is added to the last sum to create a new one. This new sum would be the number that would need to be added to it to make a multiple of ten. For example the code 63938200039 would add 6+9+8+0+0+9=32. It would multiply this sum by 3, making 32*3=96. Then it would add 3+3+2+0+3=11.  It would add 96+11=107. The number to make 107 reach the first multiple of 10 would be 3 to make 110 because 107+3=110. This would make 3 the check digit number.