Can a valid 13-digit ISBN have 'x as one of characters? [closed]

Question

can a valid 13-digit ISBN have any character other then digit 0-9? i.e., can a valid 13-digit ISBN contain character 'X'?

Middlebrow

At first sight this doesn't appear programming related, but I'm assuming you're writing something to validate ISBNs – Globefish

ISBN is a valid urn. data validation is about CS, as well as checksumming. so it's a valid question. – Chiffon

Answer 1

No, a 10-digit ISBN can, though... See http://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-13

Schild

Answer 2

No, a 13-digit ISBN uses modulo 10 in calculation of the check digit, so the check digit can be only 0 to 9. Other digits are also 0 to 9 in any versions of ISBN. See this Wikipedia article for details.

Dressy

Answer 3

No it can't - the Wikipedia page explains:

The calculation of an ISBN-13 check digit begins with the first 12 digits of the thirteen-digit ISBN (thus excluding the check digit itself). Each digit, from left to right, is alternately multiplied by 1 or 3, then those products are summed modulo 10 to give a value ranging from 0 to 9. Subtracted from 10, that leaves a result from 1 to 10. A zero (0) replaces a ten (10), so, in all cases, a single check digit results.

Globefish

and precisely where does it say so? – Inversely

This is not correct: A 13-digit ISBN cannot contain X's, only 10-digit ISBNs (since they do a mod 11 and need to display the value 10 in 1 char) – Schild

I can't find any such examples. The article says: "The International Standard Book Number (ISBN) is a unique[1] numeric commercial book identifier..." It looks like they use x as a placeholder for "any digit". – Assumpsit