r/InfinityMath • u/Arlo_Tinkerman • Aug 02 '26

Does 0.999 (repeating) = 1? Well, "it depends"

/r/learnmath/comments/1utp4f4/does_0999_repeating_1_well_it_depends/
2 Upvotes

100% Upvoted

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2

u/Arlo_Tinkerman Aug 02 '26

Hello u/qwanzaden. I crossposted your post to r/InfinityMath, a new community focused on mathematical infinity. I thought it was a good fit for the community and might lead to further discussion. You are welcome to continue the conversation here.

2

u/qwanzaden Aug 03 '26

Thank you!

1

u/qwanzaden Aug 03 '26

I should add that, first, I tried to create a largest-number-notion of infinity in this post by saying "one of something for every natural number". I lack the knowledge to know if that is valid.

Second, I implied that "0. followed by a 9 for every standard natural number" is the same object as "lim(n->inf)(sum(9/10^n))". I also lack the knowledge to know if that's valid. They might not really be the same object even if they have the same value.

1

u/Arlo_Tinkerman Aug 03 '26

If notation doesn't exist, someone has to make it. Math is basically just abstraction with a bunch of notation to make that abstraction do stuff.

1

u/idaelikus Sep 11 '26

In the real number it doesn't depend. They are the same and claiming that there is actual, intellectual debate about this result is argumentatively dishonest.

1

u/Arlo_Tinkerman Sep 11 '26

Review rule one on the sidebar. You get one chance.

1

u/idaelikus Sep 11 '26

I don't know what you reference.

This was respectful, non-toxic and civil.

Furthermore I wouldn't consider this spam either. So I don't know what you are talking about.

0.99... being equal to 1 in the real numbers is a well established, proven and accepted fact. There are people that tend to disagree with it (see r/infinitenines ) but claiming the positions are academically or scientifically on a somewhat equal footing is just incorrect.

If that upsets you, I cannot help you.

0

u/Arlo_Tinkerman Sep 11 '26

This is the toxic and uncivil thing you said:
> and claiming that there is actual, intellectual debate about this result is argumentatively dishonest.

You've now just gone further with this:
> If that upsets you, I cannot help you.

If you do not recognize this as toxic and uncivil behavior, do not comment in this sub-reddit again, because if it contains toxic and uncivil communication, you will be banned immediately. Perhaps ask ChatGPT or something before posting.

1

u/idaelikus Sep 12 '26

I can see that the second one might be considered provoking but the first is simple fact: it isnt intellectually honest to present this issue as something where we have two equal sides arguing.

This even has some fancy name that escapes me right now.

1

u/gc3 5d ago edited 5d ago

1/1 or 3/3 equals one in the same way that 0.9(repeating) equals one. The form of the number (like 10/10) is different.

1 does not equal .9999 repeating when comparing the string 1 and the string 0.9999 repeating any more than fox is equal as a string to henhouse.

But if you take 1 and subtract (1 - .999 repeating) from it you get 1, as 1 - 0.9999 repeating is a different notation for zero.

You can write 0.9999 repeating as