CheckDigits::M10_009(3) 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'

## ALGORITHM

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

None by default.

## AUTHOR

Mathias Weidner, <[email protected]>