Question: I'm really stuck on this. I could do it with integer division and multiplication but I have no idea how to find the remainder without any of these operators. (can't import anything either. the main premise is to use while loops).

Answer: 
```
>>> def solution(a, b):
...     while a >= b:
...         a -= b
...     return a
... 
>>> solution(11, 5) == (11 % 5)
True
>>> solution(763, 47) == (763 % 47)
True

```
Just an efficient one:

```
def mod(a, b):
    if a >= b:
        a = mod(a, b + b)
    if a < b:
        return a
    return a - b

```

Demo:

```
>>> a, b = 75349157395712349036170927572349157024, 543791534729045
>>> mod(a, b)
510757213184524
>>> a % b
510757213184524

```