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'?

Answer 1

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

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.