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.)


   D            =:  '0123456789'
 
   isbn13c      =:  D&([ check@:i. clean)
     check      =:  0 = 10 | lc
       lc       =:  [ +/@:* weight
         weight =:  1 3 $~ #
     clean      =:  ] -. a. -. [