True...
You don't necessarily have to start at the last digit, if you're willing to do more work, you can start at the first one (which, for simplicity of concept, we can do with numbers that expand in non-zeros)...
1.888888... + 2.333333... =
sum the 1 and 2, we get 3.
Sum the 8 and 3, we get 11, keep the second 1, add the last 1 to the last sum (to be 4).
Sum the 8 and 3, we get 11, keep the second 1, add the last 1 to the last sum (this time to be 2).
Sum the 8 and 3, we get 11, keep the second 1, add the last 1 to the last sum (again to be 2).
Sum the 8 and 3, we get 11, keep the second 1, add the last 1 to the last sum (again to be 2).
Sum the 8 and 3, we get 11, keep the second 1, add the last 1 to the last sum (again to be 2).
And it then keeps going on. We get
4.222222....
There's no problem with this, it's all good. One might say "but it goes on forever, so you can't know what comes out to be", but this isn't true. As soon as things stop changing (that is, we enter the calculation loop of the "..."), we're done, because we at that point know everything we need to know. To prove it, ask me what the value at **any** given index/digit is and I can give you an answer. Try to use numbers that expand in non-zeros with the "normal" numbers that do expand in zeros. It always works without issue.
One can't use the argument of "you get stuck" or "you can't know", because we don't ever get stuck, and we do know everything about these numbers that there is to know. They can be used in **any** mathematical operation flawlessly without a problem or "error" arising.