Python Float Division Not Exact

Possible Duplicate: Python float - str - float weirdness Python float division does not appear to have accurate results. Can someone explain why? >>>3.0/5 0.59999999999

Solution 1:

Short answer: Floats use finite-precision binary encoding to represent numbers, so various operations lose some precision.

The Wikipedia page has a lot of information (maybe too much).

See also: How do I use accurate float arithmetic in Python?

Solution 2:

Floating point arithmetic is not exact; there are rounding errors that are worsened by the fact that computers use binary floating point and not decimal floating point. See Wikipedia.