Jack really likes his number five: the trick here is that you have to multiply each number by 5 raised to the number of digits of each numbers, so, for example:
```python
multiply(3)==15
multiply(10)==250
multiply(200)==25000
multiply(0)==0
multiply(-3)==-15
```
def multiply(n):
    e = len(str(abs(n)))
    return n * 5**e
def multiply(n):
    e = len(str(abs(n)))
    return n * 5**e