# NAME

CheckDigits::M11_017 - compute check digits for EC-No, EINECS, ELINCS

# SYNOPSIS

``````  use Algorithm::CheckDigits;

\$ecno = CheckDigits('ecno');

if (\$ecno->is_valid('200-236-6')) {
# do something
}

\$cn = \$ecno->complete('200-236-');
# \$cn = '200-236-6'

\$cd = \$ecno->checkdigit('200-236-6');
# \$cd = '6'

\$bn = \$ecno->basenumber('200-236-6');
# \$bn = '200-236-'
``````

# DESCRIPTION

## ALGORITHM

1. From left to right all digits are multiplied with their position in the sequence.

3. The sum of step 2 is taken modulo 11.

The checkdigit is the last digit of the result.

## 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>`