Nt1310 Unit 3 Assignment 1 Check Digit

Another example of when a check digit is used is in barcode numbers. The majority of products that you can buy have a 13-digit number on them, which is scanned to get all the product details, such as the price. This 13-digit number is referred to as the ‘GTIN-13’ where ‘GTIN’ stands for Global Trade Item Number.

Error control is used in barcodes because without it, there would be so many errors and people would end up being charged for the wrong products. Sometimes when a barcode is being scanned, the scanner won’t read the number and therefore the number has to be entered manually, which can lead to human error. For example, if you bought a box of cereal and your cashier was entering the barcode number manually but accidently pushed a 3

The check digit is used to try and detect any errors and can be calculated through a special maths formula. To calculate the check digit, you must multiply the first barcode number by 1, the next by 3, and the next by 1, and the next by 3 and so on. Then, you add the results. Using the result, you then round this up to the nearest multiple of 10 and then subtract the result from this new multiple of 10, which gives you the check digit. I will now show you an example of how to calculate the check digit using a barcode number from a tissue box that I

I then checked that I had calculated the correct digit by entering the barcode number onto the website http://www.gs1.org/check-digit-calculator. This website confirmed that I had found the correct check digits which meant that all of these barcodes were valid and therefore would not have experienced any errors while being scanned.

When manually entering a barcode, you can easily enter it wrong which results in an error. Some errors include entering one digit wrong (substitution), missing a digit, adding a digit, or swapping two digits that are adjacent to each other (transposition).

I experimented with some of these errors and found that if you enter a barcode number too short, no matter how many digits are missing, the error will always be detected…

I also found that if you enter the barcode number too long, the error will be detected…

If swap two digits that are adjacent to each other (transposition) the check number can usually find this error, however, it depends on the numbers used. Usually, it will find the error because a different check number will be calculated. It can be seen in this example as the check number was supposed to be 2, but I swapped the last two digits around which resulted in the check digit being