python3: calculating discount between the same gross price and net price gives me a value other than 0

Question

I have the snippet of code below.
how come the result is different from 0 ?
Thank you.

>>> price_1   = float('1,36'.replace(',', '.'))  
>>> price_2   = float('1,36'.replace(',', '.'))  
>>> ret_value = 100 - (price_1 * 100 / price_2)  
>>> ret_value  
1.4210854715202004e-14