use strict;
use warnings;
use Data::Dumper;
my %totals;

for(1..10){
   @totals{qw(a b c)} += (1,2,3);
}
print Dumper \%totals;

##</code><code>##

%totals = (
   'a' => 10,
   'b' => 20,
   'c' => 30,
);
##</code><code>##

(
   'a' => undef,
   'b' => undef,
   'c' => 30,
);