Man pages sections > man3 > Algorithm::CheckDigits::MXX_004

# CheckDigits::MXX_004 - compute check digits for VAT RN (AT)

 CheckDigits::MXX_004(3pm) User Contributed Perl Documentation CheckDigits::MXX_004(3pm)

## NAME

CheckDigits::MXX_004 - compute check digits for VAT RN (AT)

## SYNOPSIS

```  use Algorithm::CheckDigits;
\$vat = CheckDigits('ustid_at');
if (\$vat->is_valid('U13585627')) {
# do something
}
\$cn = \$vat->complete('U1358562');
# \$cn = 'U13585627'
\$cd = \$vat->checkdigit('U13585627');
# \$cd = '7'
\$bn = \$vat->basenumber('U13585627');
# \$bn = 'U1358562'
```

## DESCRIPTION

### ALGORITHM

1.
Beginning right all numbers before the check digit are weighted alternatively 1 and 2.
2.
The total of the digits of all products is computed and then subtracted from 96.
3.
The check digit is the sum of step 3 taken modulo 10.

### 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.