find.pl

#!/usr/bin/env perl
use 5.010;
use strict;
use List::MoreUtils qw/zip/;
use Math::Base::Convert qw(cnv);
use Data::Dumper;

my $res = 45;
my @nums = qw(9 2 11 13 6 3);
my $max = 4 ** (@nums-1);

for( my $i=0; $i<$max; $i++ ){
        my $p = cnv($i, 10,[qw(+ - * /)]);
        $p = sprintf('%'.(@nums-1).'s',$p);
        $p =~ s/ /+/g;
        my @p = split(//,$p);
        my $z = join(' ',zip(@nums,@p));
        if( eval($z)==$res ){
                say $z . ' = ' . $res;
        }
}

find_fork.pl

#!/usr/bin/env perl
use 5.010;
use strict;
use List::MoreUtils qw/zip/;
use Math::Base::Convert qw(cnv);
use Data::Dumper;

my $res = 45;
my @nums = qw(9 2 11 13 6 3) ;
my $max = 4 ** (@nums-1);

my $start = 0;
my $end = $max;

my $min = 100;
my $i=0;
for( $i = 0; $i<$max-$min; $i+=$min ){
        if( !fork ){
                _find($res,\@nums,$i,$i+$min);
                exit;
        }
}
_find($res,\@nums,$i, $max);
wait;

sub _find{
        my $res = shift;
        my $nums = shift;
        my @nums = @{$nums};
        my $start = shift;
        my $end = shift;
        for( my $i=$start; $i<$end; $i++ ){
                my $p = cnv($i, 10,[qw(+ - * /)]);
                $p = sprintf('%'.(@nums-1).'s',$p);
                $p =~ s/ /+/g;
                my @p = split(//,$p);
                my $z = join(' ',zip(@nums,@p));
                if( eval($z)==$res ){
                        say $z . ' = ' . $res;
                }
        }
}