Elementary confusion

[Mark McEahern]

[Keith]
> I am working through O'Reilly's "Learning Python". I am up to page 33,
> and already I have a problem. The text outlines a cli entry about math
> operators, all really straight forward;
>
> .>>>a=3
> .>>>b=4
> .>>>b/2+a
>  5
> .>>>b/(2.0+a)
>  0.8
>
> This is so straight forward that I wasn't going to type it in, but I
> did anyway, and got instead of '0.8' something I cannot account for. I
> got '0.80000000000000004'.
>
> So after 32 pages, I am already flumoxed. What is going on

This is a FAQ.  Please read the FAQ.  This has to do with floating point
math:

  http://www.python.org/doc/FAQ.html#4.98

// mark