use strict;
use warnings;
use 5.010;

my @arr1 = ("1", "", "");
my @arr2 = ("", "3", "4");


for my $index (0 .. 2) {
    say $arr1[$index] + $arr2[$index];
}

--output:--
Argument "" isn't numeric in addition (+) at 2perl.pl line 10.
1
Argument "" isn't numeric in addition (+) at 2perl.pl line 10.
3
Argument "" isn't numeric in addition (+) at 2perl.pl line 10.
4

##</code><code>##

use strict;
use warnings;
use 5.010;

my @arr1 = ("1", "", "");
my @arr2 = ("", "3", "4");

for my $index (0 .. 2) {
    say int($arr1[$index]) + int($arr2[$index]);
}

--output:--
Argument "" isn't numeric in int at 2perl.pl line 9.
1
Argument "" isn't numeric in int at 2perl.pl line 9.
3
Argument "" isn't numeric in int at 2perl.pl line 9.
4

##</code><code>##

use strict;
use warnings;
use 5.010;

use List::MoreUtils qw{ pairwise };

my @arr1 = (10, 20, 30);
my @arr2 = (1, 1, 1);

my @totals = pairwise {$a + $b} @arr1, @arr2;

--output:--
Name "main::b" used only once: possible typo at 2perl.pl line 12.
Name "main::a" used only once: possible typo at 2perl.pl line 12.