Provided by: libalgorithm-checkdigits-perl_0.50-1_all

#### NAME

```       CheckDigits::M23_002 - compute check digits for VAT Registration Number (IE)

```

#### SYNOPSIS

```         use Algorithm::CheckDigits;

\$dni = CheckDigits('ustid_ie');

if (\$dni->is_valid('8473625E')) {
# do something
}

\$cn = \$dni->complete('8473625');
# \$cn = '8473625E'

\$cd = \$dni->checkdigit('8473625E');
# \$cd = 'E'

\$bn = \$dni->basenumber('8473625E');
# \$bn = '8473625'

```

#### DESCRIPTION

```   ALGORITHM
1.  Beginning right all digits are weighted with their position in the number (i.e. the
number left from the check digit is multiplied with 2, the next with 3 and so on).

3.  The check digit is the sum from step 2 modulo 23. This number is expressed as the
corresponding letter from the alphabet where A-V correspond to 1-22 and W stands for
check digit 0.

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>

```

#### SEEALSO

```       perl, CheckDigits, www.pruefziffernberechnung.de.
```