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

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'`?

Accepted Answer

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

Solution