Question 1

What is a UPC-A barcode?

Accepted Answer

UPC-A (Universal Product Code) is a 12-digit barcode used primarily in North America for retail product identification. The last digit is a check digit calculated from the first 11.

Question 2

How is the UPC check digit calculated?

Accepted Answer

Sum odd positions (1st,3rd,etc.) × 3 + sum even positions (2nd,4th,etc.). Check digit = (10 - (sum mod 10)) mod 10.