 CheckDigits::M09_001(3) compute check digits for Euro notes

## SYNOPSIS

use Algorithm::CheckDigits;
\$euro = CheckDigits('euronote');
if (\$euro->is_valid('X07738250357')) {
# do something
}
\$cn = \$euro->complete('X0773825035'); # \$cn = 'X07738250357'
\$cd = \$euro->checkdigit('X07738250357'); # \$cd = '7'
\$bn = \$euro->basenumber('X07738250357'); # \$bn = 'X0773825035'

## ALGORITHM

1.
Letters are replaced with their position in the alphabet ('A' = 1, ...).
2.
The total of the digits of all numbers is computed.
3.
This sum is taken modulo 9.
4.
The check digit is the difference between 8 and the number of step 3.

To validate the last digit of the total of the digits of all numbers inclusive check digit must be 8.

## 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.

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, <[email protected]>