check digit

check digit definition - business

check digit

A digit attached to a data item to help with error detection. For example, the last digit of a check's bank routing number is a check digit. A check digit is calculated from a formula using other digits in the number. Entry of the number causes the computer to recalculate the check digit to determine if the number has been entered correctly.
Case Study The last digit of each UPC number is a check digit used to verify that the UPC for a particular product is correct. The verification process for each 12-digit UPC code works like this: (1) the 6 digits in odd positions are added and the sum is multiplied by 3; (2) the first 5 digits in even positions are added; (3) the sums calculated in steps 1 and 2 are added; (4) the last digit (the check digit) is added to the result in step 3, and the result should equal a multiple of 10. For example, the UPC for an 18-ounce jar of Jif peanut butter is 051500241356.
Step 1: 0 + 1 + 0 + 2 + 1 + 5 = 9; 9 × 3 = 27
Step 2: 5 + 5 + 0 + 4 + 3 = 17
Step 3: 27 + 17 = 44
Step 4: The check digit of 6 is added to step 3 to equal 50, a multiple of 10.

The American Heritage® Dictionary of Business Terms Copyright © 2009 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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