Hi Monks

Newbie here, so thanks for being gentle.

I'm needing a procedure to check Australian Business Numbers (aka ABN's).

The simple algorithm is described at https://abr.business.gov.au/Help/AbnFormat

I've hacked the short procedure copied below, but I suspect it could be improved.

I don't do this often, so would be really grateful for any tips and/or clues.

TIA's 

sub Check_ABN {
    my $number = shift ;
    my $abn_invalid = 0 ;
    my $sum = 0 ;
    $number =~ s/\ //g ;
    unless (length($number) eq 11) {
        $abn_invalid = 1 ;
        return $abn_invalid ;
    }
    
    $sum += (substr($number,0,1)-1)*10 ;
    $sum += substr($number,1,1)*1 ;
    $sum += substr($number,2,1)*3 ;
    $sum += substr($number,3,1)*5 ;
    $sum += substr($number,4,1)*7 ;
    $sum += substr($number,5,1)*9 ;
    $sum += substr($number,6,1)*11 ;
    $sum += substr($number,7,1)*13 ;
    $sum += substr($number,8,1)*15 ;
    $sum += substr($number,9,1)*17 ;
    $sum += substr($number,10,1)*19 ;
    if ($sum % 89 eq 0) {
        return $abn_invalid ;
    } else {
        $abn_error = 1 ;
        return $abn_invalid ;
    }
    # see https://abr.business.gov.au/Help/AbnFormat
}

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In reply to ABN checker by bgroper

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