## Wednesday, September 12, 2018

### Resolve Invalid Barcodes When Printing Item Labels

If users are unable to print item labels, the item barcode may be invalid. A barcode is invalid when its check digit is incorrect. A check digit is a number appended to the data contained in a barcode. A Check digit is used to assure accuracy; to "check" for errors. It typically consists of a single digit computed from the other digits in the data.

To check if a barcode is valid, consider the following:

• For 12 digit bar codes (UPCA types of bar codes)
• Sample bar code is 134688257347

1.    Add the digits in the odd-numbered positions (first, third, fifth, etc.) together and multiply the total by three.

1+4+8+2+7+4=26

2.    Multiply what you got on step 1 by 3

26 * 3 = 78

3.    Add the digits in the even-numbered positions (second, fourth, sixth, etc.).

3+6+8+5+3=25

4.    Add the two results together.

78 + 25 = 103

5.    Now what single digit number makes the total a multiple of 10? That's the check digit.

103, to make it a multiple of 10, it needs 7

7 is the check digit that must be the last digit of the bar code

• For 13 digit bar codes (EAN type)
• Sample bar code 1346882573478

1.    Starting from the second position, add all the digits  in an even-numbered positions  (second, fourth, sixth) together.

3+6+8+5+3+7=32

2.    Multiply what you got on step 1 by 3

32*3=96

3.    Add all the digits in an the odd-numbered positions  together

1+4+8+2+7+4=26

4.    Add the two results together

96+26=122

122, to make it a multiple of 10, it needs 8

8 is the check digit that must be the last digit of the bar code