Checksum calculation drops leading zero, just look at attached example.
| Subject: | ibantest.pl |
use Business::IBAN;
my $bban = "105000995383300000000006";
my $iban = Business::IBAN->new();
my $full = $iban->getIBAN({
ISO => "PL",
BBAN => $bban,
});
print "$full\n";
# simple way:
use bignum;
my $pl = "2521";
my $s = $bban.$pl."00";
printf "IBAN PL%02d%s\n", 98-($s % 97), $bban;