Python 2.7.12 (default, Jul  1 2016, 15:12:24) 
  [GCC 5.4.0 20160609] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  >>> 0.3 - 0.1

0.19999999999999998

Python 3.5.1 yields the same result