I think you mean “they must both be positive” here, but 0.999… isn’t guaranteed to be an integer a priori.
Aside from that, everything you’ve said is basically correct. But… well, there’s something pretty interesting going on with infinite decimals to the left. For numbers that don’t exist they sure do have a lot of interesting properties. This might be worth a top-level post.
I think you mean “they must both be positive” here, but 0.999… isn’t guaranteed to be an integer a priori.
Aside from that, everything you’ve said is basically correct. But… well, there’s something pretty interesting going on with infinite decimals to the left. For numbers that don’t exist they sure do have a lot of interesting properties. This might be worth a top-level post.