use strict;
use warnings;
use Time::HiRes 'time';

my $start = time();
my @ret = map { $_ * 2 } 1..10_000_000;

printf "%s %s\n", $ret[5_000_000], $ret[-1];
printf "%0.3f seconds\n", time() - $start;

__END__
10000002 20000000
0.561 seconds