Python math is off by .000000000000045

[Alec Taylor]

Simple mathematical problem, + and - only:

>>> 1800.00-1041.00-555.74+530.74-794.95
-60.950000000000045

That's wrong.

Proof
http://www.wolframalpha.com/input/?i=1800.00-1041.00-555.74%2B530.74-794.95
-60.95 aka (-(1219/20))

Is there a reason Python math is only approximated? - Or is this a bug?

Thanks for all info,

Alec Taylor