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# Manual Reference Pages  -  ALGORITHM::CHECKDIGITS::M10_002 (3)

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### NAME

CheckDigits::M10_002 - compute check digits for CINS (US), SIREN (FR), SIRET (FR)

### SYNOPSIS

```

use Algorithm::CheckDigits;

\$siret = CheckDigits(siret);

if (\$siret->is_valid(73282932000074)) {
# do something
}

\$cn = \$siret->complete(7328293200007);
# \$cn = 73282932000074

\$cd = \$siret->checkdigit(73282932000074);
# \$cd = 4

\$bn = \$siret->basenumber(73282932000074);
# \$bn = 7328293200007

```

### DESCRIPTION

#### ALGORITHM

 1. Beginning right all numbers are weighted alternatively 1 and 2. 2. The total of the digits of all products is computed. 3. The sum of step 3 ist taken modulo 10. 4. The check digit is the difference between 10 and the number from 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.

### AUTHOR

Mathias Weidner, <mamawe@cpan.org>