Using real numbers, 0.999… is absolutely one. Limits are involved in the proof, but aren’t necessary for the original statement. But, as pointed out by William, there are other number systems (hyperreal, superreal, surreal) that have an infinite number of numbers between 0.999… and 1. The defiance shouldn’t be to come up with such numbers (in Hakenstrings, 10(1) followed by any combination of 0s and 1s), but rather to find a use for them in CS.