Question

Why does this simple calculation return 0

>>> 25/100*50  
0

while this actually calculates correctly?

>>> .25*50
12.5

>>> 10/2*2  
10

What is wrong with the first example?

Answer 1

In Python 2, 25/100 is zero when performing an integer divison. since the result is less than 1.

You can “fix” this by adding from __future__ import division to your script. This will always perform a float division when using the / operator and use // for integer division.

Another option would be making at least one of the operands a float, e.g. 25.0/100.

In Python 3, 25/100 is always 0.25.