Man pages sections > man3 > Algorithm::CheckDigits::M11_011

# CheckDigits::M11_011 - compute check digits for VAT Registration Number (NL)

 CheckDigits::M11_011(3pm) User Contributed Perl Documentation CheckDigits::M11_011(3pm)

## NAME

CheckDigits::M11_011 - compute check digits for VAT Registration Number (NL)

## SYNOPSIS

```  use Algorithm::CheckDigits;
\$ustid = CheckDigits('ustid_nl');
if (\$ustid->is_valid('123456782')) {
# do something
}
if (\$ustid->is_valid('123456782B04')) {
# do something
}
\$cn = \$ustid->complete('12345678');
# \$cn = '123456782'
\$cn = \$ustid->complete('12345678.B04');
# \$cn = '123456782B04'
\$cd = \$ustid->checkdigit('123456782');
# \$cd = '2'
\$cd = \$ustid->checkdigit('123456782B04');
# \$cd = '2'
\$bn = \$ustid->basenumber('123456782');
# \$bn = '12345678';
\$bn = \$ustid->basenumber('123456782B04');
# \$bn = '12345678.B04';
```

## DESCRIPTION

This VATRN has 12 "digits", the third last must be a B, the fourth last is the checkdigit. I don't know anything about the meaning of the last two digits.
You may use the whole VATRN or only the first eight digits to compute the checkdigit with this module.

### ALGORITHM

1.
Beginning right with the digit before the checkdigit all digits are weighted with their position. I.e. the digit before the checkdigit is multiplied with 2, the next with 3 and so on.
2.
The weighted digits are added.
3.
The sum from step 2 is taken modulo 11.
4.
If the sum from step 3 is 10, the number is discarded.

### 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 the check digits of \$number if \$number has valid check digits.

Return '' otherwise.

None by default.