Man pages sections > man3 > Algorithm::CheckDigits::M11_008

# CheckDigits::M11_008 - compute check digits for VAT Registration Number (DK)

 CheckDigits::M11_008(3pm) User Contributed Perl Documentation CheckDigits::M11_008(3pm)

## NAME

CheckDigits::M11_008 - compute check digits for VAT Registration Number (DK)

## SYNOPSIS

```  use Algorithm::CheckDigits;
\$ustid = CheckDigits('ustid_dk');
if (\$ustid->is_valid('13585628')) {
# do something
}
\$cn = \$ustid->complete('1358562');
# \$cn = '13585628'
\$cd = \$ustid->checkdigit('13585628');
# \$cd = '8'
\$bn = \$ustid->basenumber('13585628');
# \$bn = '1358562';
```

## DESCRIPTION

### ALGORITHM

1.
Beginning left every digit is weighted with 2, 7, 6, 5, 4, 3, 2, 1
2.
3.
The sum from step 2 is taken modulo 11.
4.
The number is valid if the sum from step 3 is zero (0).

### METHODS

is_valid(\$number)
Returns true only if \$number consists solely of numbers and hyphens and the two digits in the middle are valid check digits according to the algorithm given above.

Returns false otherwise,
complete(\$number)
The check digit for \$number is computed and inserted into the middle of \$number.

Returns the complete number with check digit or '' if \$number does not consist solely of digits, hyphens and spaces.
basenumber(\$number)
Returns the basenumber of \$number if \$number has a valid check digit.

Return '' otherwise.
checkdigit(\$number)
Returns '' if \$number is valid.

Return undef otherwise.

None by default.