Can anyone explain to me how this Php code equates to 3?

Question

Just had this question for a php challenge, and I can’t figure out how you get 3 from It. I understand one of the numbers you’ll get back from the function Is 5, but I don’t get how 3 Is the answer unless somehow sum returns a result of 15 to then be divided by 3.
//code start
function sum($from, $number) {
$result = 0;
for($i = $from; $i <= $number; i++) {
$result = $result + $i;
}
return $result;
}
echo sum(0, 5) / 5;
//code end

Any help is appreciated, thanks.

Answer 1

Sum() return 15.
For loop go over i=0,i=1,i=2,i=3,i=4,i=5
And result is the sum of all the i
Result=0+1+2+3+4+5=15
Then 15/5=3

And the output is 3

Answer 2

Yes, the output of the function is 15, so you echo 15 / 5 = 3

Now let me explain why it does return 15:
Inputs / variables:

$from = 0 (input)
$number = 5 (input)
$result = 0

Now the loop:
for($i = from; $i <= $number; $i++)

Enter the vars and you get
for($i = 0; $i <= 5; i++)

Now I'm going to explain loops just to be sure:
This will loop 6 times because:
1st time: $i = 0. Is $i <= 5? No: loop and i++ (=1)
2nd time: $i = 1, ... <= 5? No: loop and i++ (=2)
6th time: $i = 5, ... <= 5? No (= 5): now loop and make $i 6, so a 7th time (6 <= 5 is false) won't happen

Now what it does in the loop:

$result = $result + $i or
$result += $i
(different way of writing the same)

So it will go like this:
1st: $result (=0) += $i (=0) --> 0 + 0 = 0
2nd: $result (=0) += $i (=1) --> 0 + 1 = 1
3th: $result (=1) += $i (=2) --> 1 + 2 = 3
4th: $result (=3) += $i (=3) --> 3 + 3 = 6
5th: $result (=6) += $i (=4) --> 6 + 4 = 10
6th: $result (=10) += $i (=5) --> 10 + 5 = 15

Return this number, which is 15