NAME

       CheckDigits::M10_009 - compute check digits for Betriebsnummer (DE)

SYNOPSIS

         use Algorithm::CheckDigits;

         $betrnr = CheckDigits('betriebsnummer');

         if ($betrnr->is_valid('73282932000074')) {
               # do something
         }

         $cn = $betrnr->complete('7328293200007');
         # $cn = '73282932000074'

         $cd = $betrnr->checkdigit('73282932000074');
         # $cd = '4'

         $bn = $betrnr->basenumber('73282932000074');
         # $bn = '7328293200007'

DESCRIPTION

   ALGORITHM
       1.  Beginning left all numbers are weighted alternatively 1 and 2.

       2.  The total of the digits of all products is computed.

       3.  The sum of step 3 ist taken modulo 10.

       4.  The check digit is the difference between 10 and the number from step 3 taken modulo
           10.

           HINT: The last digit of the 'Betriebsnummer' may be the check digit or the last digit
           of the sum of the constant 5 and the check digit.

   METHODS
       is_valid($number)
           Returns true only if $number consists solely of numbers and the last digit is a valid
           check digit according to the algorithm given above.

           Returns false otherwise,

       complete($number)
           The check digit for $number is computed and concatenated to the end of $number.

           Returns the complete number with check digit or '' if $number does not consist solely
           of digits and spaces.

       basenumber($number)
           Returns the basenumber of $number if $number has a valid check digit.

           Return '' otherwise.

       checkdigit($number)
           Returns the checkdigit of $number if $number has a valid check digit.

           Return '' otherwise.

   EXPORT
       None by default.

AUTHOR

       Mathias Weidner, <mathias@weidner.in-bad-schmiedeberg.de>

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de.
       www.dsi.cnrs.fr/bureau_qualite/admindonnees/documents/siren.pdf