 # JS: Trouble understanding what happens in a Loop

Hi there, newbie codeacademy user here. I’m trying to learn JS as my first language, im enjoying quite a lot, but i’ve got some trouble with loops. There is an exercise in the “practice” section, wich i cannot understand whats going on: Here is the code:

const values = [1, 10, 4, 3, 15, 3, 5, 2];

let total = 100
for (let i = values.length - 2; i >= 0; i -= 2) {
let a = values[i];
total /= a;
total += 10;
}
console.log(total);

So here: (i’ll try to do my best to explain)
i = 6, 4, 2, 1
a = 5, 15, 4, 1

Then maths are: (according for what i understand, obviously i’m missing something)
Divisions:
100 / 5 = 20
100 / 15 = 6,666…
100 / 4 = 25
100 / 1 = 100

Sums
20 + 10 = 30,
6,66 + 10 = 16,666
25 + 10 = 35
100 + 10 = 110

BUT the correct answer is 23. I’m lost at this point. What happens with all the values i got from the loop? They sum to show the value of total outside the block? Are the maths ok?
Loops are where i’m getting more trouble to understand what going on, please someone could bring some light here and explain whats going on?