Have you ever looked at the back of a book and above the barcode there is a number? Well, that is how books are classified internationally. Prior to 2007, ISBN-10 (International Standard Book Number) was standard. With it now being phased out, ISBN-13 has taken its spot! ISBN-10 is still common today, with books being published with both ISBN-10 and ISBN-13 on the back! Did you also know that the validity of ISBN-10 can be figured out by math? I would like to show you how! For this example, we will be using this ISBN-10.
To figure out if an ISBN-10 number is valid you have to follow these steps!
First, write down the whole ISBN-10 number.
Remove the dashes.
Second, similar to UPCs, Bank Routing Numbers, and Money Orders, you have to multiply the ISBN-10 by the weight!
In ISBN-10, The weight is: 10,9,8,7,6,5,4,3,2,1.
(I will put it in a grid to make it easier to visualize)
Third, add all of the products together!
Finally, divide the number by 11, and if the number divides evenly by 11, (meaning there is no remainder) then it is valid!
(This isn’t the only way to check for validity with an ISBN-10 number, but it is a quick way to identify the validity of the book!)
Now that you know how to identify the validity of a book, you can now buy a book knowing how to identify it and how to make sure it is valid!