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Re:0.999...= 1 by brutt on Tuesday April 28, 2020 @12:26PM (#23008608)

    0.999... + 0.000...1 = 1
    0.000...1 = 1/∞
    0.999... = 1 - 1/∞
1/∞ is zero or not?
Re:0.999...= 1 by brabel on Tuesday April 28, 2020 @01:46PM (#23009675)
If you accept that

1/∞ = 0

Then you accept that

∞ * 0 = 1

But the definition of 0 is exactly that anything multiplied by it must be 0. So this cannot be true.

To take a more verbal route: you cannot take nothingness and repeat it. Repeating (or multiplying) nothingness (or 0) is fundamentally nonsense.

Programmer explanation: one cannot loop through `null` even once, let alone a large number.

Re:0.999...= 1 by aliceryhl on Tuesday April 28, 2020 @02:08PM (#23009930)
No, you don't have to accept that. In my Analysis 2 course we worked a whole bunch with [0, ∞], i.e. the positive real numbers together with infinity, and we defined 1/∞ = 0 and ∞ * 0 = 0. You lose some of your usual rules of arithmetic, but it gets a lot easier to talk about integrals.
Re:0.999...= 1 by brutt on Tuesday April 28, 2020 @02:14PM (#23010015)
https://en.wikipedia.org/wiki/Surreal_number

Quote:

There are also representations like

{ 0, 1, 2, 3, … | } = ω

{ 0 | 1, 1/2, 1/4, 1/8, … } = ε

where ω is a transfinite number greater than all integers and ε is an infinitesimal greater than 0 but less than any positive real number. Moreover, the standard arithmetic operations (addition, subtraction, multiplication, and division) can be extended to these non-real numbers in a manner that turns the collection of surreal numbers into an ordered field, so that one can talk about 2ω or ω − 1 and so forth.

Re:0.999...= 1 by aliceryhl on Tuesday April 28, 2020 @02:22PM (#23010110)
I'm not quite sure I understand what you're trying to tell me? The example I mentioned is not about surreal numbers.
Re:0.999...= 1 by drran on Tuesday April 28, 2020 @04:27PM (#23011538)
I recommend watching this lecture about surreal numbers by John Conway: https://www.youtube.com/watch?v=1eAmxgINXrE .
Re:0.999...= 1 by ramshorns on Tuesday April 28, 2020 @04:29PM (#23011560)
There are some weird rules like that for floating point numbers too.
Re:0.999...= 1 by empath75 on Tuesday April 28, 2020 @08:39PM (#23013931)
What on earth is .000...1

If it terminates it’s not an infinite series. In any case, if you add any finite number to .99999... it’ll be equal to 1 + that number.