Addressing just the point at issue and ignoring the vast majority of your "sample" code, the following demonstrates how you can handle an arbitrary number of columns (equivalent of your multiple input files perhaps) over an arbitrary number of rows by using an array of array:

use strict;
use warnings;

my @rows;

while (<DATA>) {
    chomp;
    next unless length;

    my @columns = split ' ';
    push @rows, \@columns;
}

printf " %2d ", $_ for 1 .. @{$rows[0]};
print "  sum\n";

for my $row (@rows) {
    my $sum;

    $sum += $_ for @$row;
    printf " %3d", $_ for @$row;
    printf " %4d\n", $sum;
}

__DATA__
 218 156 350 994 137 729 656 977 582 957
  80  10 686 679 881 486 272 927 971 153
 136 694 724 326 536  99 620 564 290 703
 402 835 397 291 886 714 580 861  80 634
 651 144 787 722 125 397 323 261 969 782
[download]

Prints:

  1   2   3   4   5   6   7   8   9  10   sum
 218 156 350 994 137 729 656 977 582 957 5756
  80  10 686 679 881 486 272 927 971 153 5145
 136 694 724 326 536  99 620 564 290 703 4692
 402 835 397 291 886 714 580 861  80 634 5680
 651 144 787 722 125 397 323 261 969 782 5161
[download]