It's not limitlessly expanding; it's not expanding at all. It is a constant number, just infinitely long. 0.9r is a fixed value, it doesn't change.
Your question is meaningless, we are not talking about limits in reality (as in, the physical world), we are talking about infinity as a mathematical concept. Technically speaking, there is no space for any number, since numbers don't exist except in the mind. The concept of infinity is an endless supply of something, be it size or length.
There isn't an end for it at all, so you can't put a number on the "end" of it. Your misconception is that infinitely long numbers aren't finite values, when they are. 0.9r is infinitely long, but it has a finite value, since 2 is a larger value (and by definition an infinite value is the largest value). Your second misconception is that there is only one way of representing a value in the decimal system, when there are many ways of doing so.
Your question is meaningless, we are not talking about limits in reality (as in, the physical world), we are talking about infinity as a mathematical concept. Technically speaking, there is no space for any number, since numbers don't exist except in the mind. The concept of infinity is an endless supply of something, be it size or length.
There isn't an end for it at all, so you can't put a number on the "end" of it. Your misconception is that infinitely long numbers aren't finite values, when they are. 0.9r is infinitely long, but it has a finite value, since 2 is a larger value (and by definition an infinite value is the largest value). Your second misconception is that there is only one way of representing a value in the decimal system, when there are many ways of doing so.