Decimal arithmatic, was Re: Python GUI app to impress the boss?

[Paul Rubin]

"Chris Gonnerman" <chris.gonnerman at newcenturycomputers.net> writes:
> > >>> (.70 * .05) + .000000001
> > 
> > rounds to the right thing.
> 
> Cool.  Now PROVE that's right in all cases.

What do you mean by "right"?  What do you mean by "all cases"?

> Like I said, decimal arithmetic is STILL the only choice.

I'm not convinced decimal arithmetic is "right in all cases".