Simple question

Tue Apr 15 14:30:36 EDT 2014

On 2014年04月15日 19:18, Phil Dobbin wrote:
> Hi, all.
>> I've just started to learn Python (I'm reading Mark Lutz's 'Learning
> Python' from O'Reilly) & I'm confused as to this part:
>> '>>> 0.1 + 0.1 + 0.1 - 0.3
> 5.55111.....'
>> Using 'import Decimal' you can get a much closer result i.e.
> 'Decimal('0.0')'
>> What I'm wondering is why the first calculation that arrives at
> '5.55111...' is so far out?

The `...` elides the exponent:
 >>> 0.1 + 0.1 + 0.1 - 0.3
 5.551115123125783e-17
If you copied that verbatim directly out of a book, that's just sloppy editing.
-- 
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
 -- Umberto Eco