use Algorithm::Combinatorics qw(permutations);

use strict;

my @numbers = qw(9 -4 8 6 10);
my @operators = qw(+ - * /);
my $total = 7; #required result

my $num_iter = permutations(\@numbers);
while (my $nums = $num_iter->next){
	my $op_iter = permutations(\@operators);
	while (my $ops = $op_iter->next) {
		my $str = $nums->[0];
		$str = "($str $ops->[$_] " . $nums->[$_+1] . ")" for (0..3);

		if ($total == eval $str) {
			print "$str = $total\n";
		}
	}
}