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.)


ISBN13_check_digit(n){
	for i, v in StrSplit(RegExReplace(n, "[^0-9]"))
		sum += !Mod(i, 2) ? v*3 : v
	return n "`t" (Mod(sum, 10) ? "(bad)" : "(good)")
}