What exactly is "exact" (was Clean Singleton Docstrings)

[Random832]

On Mon, Jul 18, 2016, at 00:46, Ben Finney wrote:
> What is “those”? The measurement is imprecise, the observations are
> inexact.
> 
> It makes no sense to say that a number is inexact. Exactness is not a
> property of a number.

There's no reason it shouldn't be a property of an object of a numeric
type available in a programming environment though.