Other loop with unexpected output - php

Question

I've this code and I don't understand the output. I was expecting an output 121.
I looking to understand this specific function and not the factorial function.
Code:
function a($num) {
static $totFac = 1;
if($num > 0){
$totFac = $totFac * $num;
a($num - 1);
}
$totFac++;
return $totFac;
}
$result = a(5);
echo 'result: '.$result;
Output:
126

Answer 1

First of all, the factorial of 5 is 120 explained as:
5! = 5 x 4 x 3 x 2 x 1 = 120
Second, this is how a factorial should look like with recursive call:
function factorial($number) {
if ($number < 2) {
return 1;
} else {
return ($number * factorial($number-1));
}
}
If you don't mean factorial, then this is how it happens if I alter your function
function a($num) {
static $totFac = 1;
if($num > 0){
$totFac = $totFac * $num;
echo "calc totFac: " . $totFac . "\n";
a($num - 1);
}
$totFac++;
echo "increment totFac: " . $totFac . "\n";
return $totFac;
}
$result = a(5);
echo 'result: '.$result;
This is the output of the echo
calc totFac: 5
calc totFac: 20
calc totFac: 60
calc totFac: 120
calc totFac: 120
increment totFac: 120
increment totFac: 121
increment totFac: 122
increment totFac: 123
increment totFac: 124
increment totFac: 125
result: 126

Answer 2

<?php
function a($num) {
static $totFac = 1;
if($num > 0){
$totFac = $totFac * $num;
echo 'totfac: '.$totFac . "<br>";
return a($num - 1); //you have to return here to stop execution
} else {
$totFac++;
return $totFac;
}
}
$result = a(5);
echo 'result: '.$result;
?>
Look at the comment for explaination