[David M]

0.999999 ad nauseum is a repeating decimal which is going out to infinity which by definition means that it is equal to 1. It is not equal to 0.99999 because the last digit never ends...it extends to infinity. To say it is equal to 0.9999 is to say it ends...which it does not end. It goes on forever.

Mathematically, it is the number 1. It's not even debatable. Ask any mathematician.

This is simply another way of describing the number one. Many equivalent things in mathematics can be described differently but in the end, you are describing the same thing. You have to remember, math is a way of describing things which can be quantified. One unit of anything can be descibed in many different ways using mathematics....NOT solely by describing one unit of something with the number "1". 0.99999..out to infinty is another way of describing the number one without actually using the description of "1"

Can a vehicle be called an automobile and a car?..can both be an accurate description? Yes. Can one unit of something be described be described as "1" and can it be described as 0.99999 out to infinity?...yes. Both are accurate descriptions of a concept called "one"

Its easy to forget that numbers do not exist unto themselves, they are concepts assigned to something in the physical or abstract world. A description is not a "thing". There are equivalent things in this world and equivalent descriptions. Don't confuse the two. Some here are trying to say that equivalent descriptions are not the same thing...which is not true.

Infinity is a difficult concept just like black holes and time not being linear. But it exists.