If you have .9 repeating into infinity, then it would be infinitely accurate. But, mathematics says that .9 repeating actually equals 1. Therefore, .9 repeating, despite an infinitely small amount of difference between the two, actually equals 1, despite it being infinitely accurate.
so, .9 repeating must be an infinitely accurate .9, but also must be one.
You can imagine that mathematicians would be right, but I have never heard a real solution that definitively proves that .9->=1.