My code works fine, but my general doubt is how does the modulus works?

For example:

If I take digit_sum(432)

After 2 iterations - sum = 5 and n = 4

so in the next iteration why is 4%10 is = 4

I expected it to be 0 or some absurd value like 6(10-4 = 6)

```
def digit_sum(n):
sum = 0
while n>0:
r= n%10
sum = sum +r
n=n/10
return sum
```