My solution did not use an array. The contents of $data{$key} are a single scalar value (the running total of values for the given key). So, my code is not keeping track of how many data entries that are encountered for a given value of $key.

Here is a modified version of my code that will print out the information you request. Note, I'm still not using arrays. In this code, $data{$key} contains a hash reference with keys size and total. The value of size is the current number of elements found for the given $key. The value of total is the current total of values that have been encountered for the given $key.

#!/usr/bin/env perl

use strict;
use warnings;

open my $fh, '<', 'test_file.txt' or die 'Can not open file';

my %data;
my $row_number = 1;
my $grand_total = 0;
while(<$fh>){
    chomp $_;
    my ($key, $val) = split(/\|/, $_);
    $data{$key}->{'size'}++;
    $data{$key}->{'total'} += $val;
    $grand_total += $val;
    print "Row ($row_number) ".
          "/ Array Size [$data{$key}->{'size'}] key ($key) ".
          "/ Amount ($val) / Sub Total ($data{$key}->{'total'}) ".
          "/ Grand_Total = ($grand_total)\n"; 
    ++$row_number;
}

foreach my $key ( sort { $a <=> $b } keys %data ){
    print "the total is: (".$data{$key}->{'total'}.")\n";
}

exit;
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