Task

Validate the check digit of an ISBN-13 code:

   Multiply every other digit by  3.
   Add these numbers and the other digits.
   Take the remainder of this number after division by  10.
   If it is  0,   the ISBN-13 check digit is correct.


Use the following codes for testing:

   978-1734314502       (good)
   978-1734314509         (bad)
   978-1788399081       (good)
   978-1788399083         (bad)


Show output here, on this page



See also

   for details:   13-digit ISBN method of validation.       (installs cookies.)


ClearAll[ValidISBNQ]
ValidISBNQ[iban_String] := Module[{i},
  i = StringReplace[iban, {" " -> "", "-" -> ""}];
  If[StringMatchQ[i, Repeated[DigitCharacter]],
   i = ToExpression /@ Characters[i];
   i[[2 ;; ;; 2]] *= 3;
   Mod[Total[i], 10] == 0
   ,
   False
   ]
  ]
ValidISBNQ["978-1734314502"]
ValidISBNQ["978-1734314509"]
ValidISBNQ["978-1788399081"]
ValidISBNQ["978-1788399083"]