For all those wondering: We are talking about 0.9 recurring. So 0.9999... with infinite nines. This means that the gap between 0.999... and 1 must be infinitely small and anything that is infinitely small is basically nonexistent. If the gap is basically nonexistent then are effectively they are the same number. While, yes they aren't exactly equal, they are in essence the exact same thing and can be used in the same way. For example, 1/3 = 0.333333... , however 0.333333...*3=? Well technically it equals 0.999999... however it also equals 1. Like I said because they are so similar they can be used as the same number. While 0.99999...≠1, 0.99999...≈1 It's like if you had 1.0000000...with infinite zeros. It's still 1. Same thing applies just in the other direction.