pedro at microboard:~$ /usr/bin/python3 Python 3.3.2+ (default, Feb 28 2014, 00:52:16) [GCC 4.8.1] on linux Type "help", "copyright", "credits" or "license" for more information. >>> 1-0.95 0.050000000000000044 >>> How to get 0.05 as result? bc has scale=2 . Has Python some similar feature?