Here is standupmaths comic Matt Parker doing calculations in his head including a bar code calculation.

Thanks to Matt making the barcode calculations look EASY Mathspig spent about 12 hours blowing steam out her ears and tearing up packaging trying to get the barcode maths to work.

This is THE absolute best exercise to test accuracy in simple calculations including transcribing numbers, which are so easily misread. It also shows you how BARCODES work.

The cash register pings if the BARCODE CHECK DIGIT Algorithm matches the CHECK DIGIT, which is the last digit in the barcode. This is how the cash register computer checks that the data in the barcode has been transferred correctly. All data transfers have some sort of data check algorithm.

The PING is KING!!!!!!!!

Mathspigs, you can check your maths skills by picking up the nearest product with a 13-digit barcode and calculating the CHECK DIGIT. The answer is at the end of the barcode.