use 5.014;
use warnings;

my ($sum, $count) = (0,0);

while (<DATA>) {
    $sum += $_;
    $count++;
    if ($count == 5) {
        printf "Sum: %4d, count: %2d, mean: %5.1f\n", 
            $sum, $count, $sum/$count;
        $sum = 0;
        $count = 0;
    }
}
printf "Sum: %4d, count: %2d, mean: %5.1f\n", 
    $sum, $count, $sum/$count;

__DATA__
61
23
30
444
368
438
467
44
812
430
992
469

##</code><code>##

      Sum:  926, count:  5, mean: 185.2
      Sum: 2191, count:  5, mean: 438.2
Final Sum: 1461, count:  2, mean: 730.5