In reply to:

We would still say we had one couch.


...and that is why I say that they are the same in any conceivable, everyday aspect. Of course if you are talking about real couches, 0.99999999999999 of a couch is macroscopically indistinguishable from 1.00000000 of a couch.

What I am saying is that strictly speaking, in the abstract world of mathematics, there is a difference between the following numbers:

2.99999
3
3.00001

To prove my point, here is a function which will return a different value depending on which of the three above numbers you plug in: f(x)=3/(x-3)

Now if those three numbers were truly the same, then you should get the same result from the function above, but you don't.

3/(2.99999-3) = 3/(-0.00001) = (-300,000)

3/(3 -3) = 3/(0) = not defined/infinity/or, you go to jail for dividing by zero and your mother is very disappointed

3/(3.00001-3) = 3/(0.00001) = 300,000