You can simplify all the dereferencing if you use a while loop with each rather than a for loop. With this method, you cannot sort the keys, but in your case, that is OK. 
use strict;
use warnings;
use Test::More tests => 2;

my $month_total    = 0;
my $day_week_total = 0;
my $VAR1 = {
    'Adam' => {
        'days'  => 22,
        'weeks' => 5,
        'total' => 22
    },
    'Keas' => {
        'total'  => 114,
        'test'   => 2,
        'weeks'  => 8,
        'days'   => 107,
        'months' => 5
    },
    'Tim' => {
        'total'  => 4,
        'weeks'  => 5,
        'days'   => 3,
        'months' => 1
    },
    'Sum' => {
        'total'  => 440,
        'days'   => 365,
        'months' => 9
    }
};

while (my ($name, $hash) = each %$VAR1) {
    next if $name eq 'Sum';
    if (exists $hash->{months}) {
        $month_total += $hash->{months};
    }
    if (exists $hash->{days} and exists $hash->{weeks}) {
        $day_week_total += ($hash->{days} + $hash->{weeks});
    }
}

ok($month_total == 6, 'month_total');
ok($day_week_total == 150, 'day_week_total');

OUTPUT:
1..2
ok 1 - month_total
ok 2 - day_week_total

[download]
Bill

In reply to Re^3: How to loop through hash of hashes and add the values based on condition? by BillKSmith
in thread How to loop through hash of hashes and add the values based on condition? by Sami_R

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