I've hit the wall of incomprehension.

Okay, I seriously need help here. I plugged the code in for this portion of the quiz to my own local machine, and so got the correct answer. BUT.

I absolutely have no [expletive deleted] idea HOW or WHY.

I took things as incrementally as I feel like I possibly could have, and even went so far as to var_dump everything and make notes to myself so I could figure out what was (or wasn't) happening. Like so:

<?php

$numbers = array(1,2,3,4);
$total = count($numbers);
$sum = 0;
$loop = 0;

foreach($numbers as $number) {
    $loop = $loop + 1;
    if ($loop < $total) {
        $sum = $sum + $number;
    }
}

var_dump($number);
echo " <--- this one is 'number'" . "</br>";
var_dump($loop);
echo " <--- this one is 'loop'" . "</br>";
var_dump($loop + 1);
echo " <--- this one is 'loop plus one'" . "</br>";
var_dump($total);
echo " <--- this one is 'total'" . "</br>";
var_dump($sum);
echo " <--- this one is 'sum'" . "</br>";
var_dump($sum + $total);
echo " <--- this one is 'sum plus total.' Allegedly." . "</br>";
//echo $sum;

And it all checks out, and got all of this as my output:

• int(4) <--- this one is 'number'
• int(4) <--- this one is 'loop'
• int(5) <--- this one is 'loop plus one'
• int(4) <--- this one is 'total'
• int(6) <--- this one is 'sum'
• int(10) <--- this one is 'sum plus total.' Allegedly.

I'm certainly no mathemagician, but if my basic arithmetic is correct, "$sum" starts out as 0, and remains at 0 once the loop runs...and $number is 4 once the loop runs...so...how do the laws of time and space bend so that 0 + 4 = 6?!? (Since, y'know, that's presumably what the "$sum" + "$number" adds up to for the "correct" answer.) My brain is melting. Please advise. Thanks very much in advance.