CheckDigits::M11_013(3pm) User Contributed Perl Documentation CheckDigits::M11_013(3pm)

# NAME¶

CheckDigits::M11_013 - compute check digits for VAT Registration Number (GR)

# SYNOPSIS¶

```  use Algorithm::CheckDigits;
\$ustid = CheckDigits('ustid_gr');
if (\$ustid->is_valid('123456783')) {
# do something
}
\$cn = \$ustid->complete('12345678');
# \$cn = '123456783'
\$cd = \$ustid->checkdigit('123456783');
# \$cd = '3'
\$bn = \$ustid->basenumber('123456783');
# \$bn = '12345678';
```

# DESCRIPTION¶

## ALGORITHM¶

1.
Beginning right with the digit before the checkdigit all digits are weighted with 2 ** position. I. e. the last digit is multiplied with 2, the next with 4, then 8 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 greater than 9, the check sum is 0 else it is the sum itself.

## METHODS¶

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,

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.

Returns the basenumber of \$number if \$number has a valid check digit.

Return '' otherwise.

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

Return '' otherwise.

None by default.