The other comments are correct: is undefined. Similarly, the limit of as approaches is also undefined. However, if you take the limit of as approaches zero from the left or from the right, you get negative and positive infinity respectively.

Answer from Ethan Brown on Stack Exchange
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Reddit
reddit.com › r/learnmath › why do we say 1/0=undefined instead of 1/0=infinity?
r/learnmath on Reddit: Why do we say 1/0=undefined instead of 1/0=infinity?
October 24, 2020 -

Like 10/2- imagine a 10 square foot box, saying 10 divided by 2 is like saying “how many 2 square foot boxes fit in this 10 square foot box?” So the answer is 5.

But if you take the same box and ask “how many boxes that are infinitely small, or zero feet squared, can fit in the same box the answer would be infinity not “undefined”. So 10/0=infinity.

I understand why 2/0 can’t be 0 not only because that doesn’t make and since but also because it could cause terrible contradictions like 1=2 and such.

Ah math is so cool. I love infinity so if anyone wants to talk about it drop a comment.

Edit: thanks everyone so much for the answers. Keep leaving comments though because I’m really enjoying seeing it explained in different ways. Also it doesn’t seem like anyone else has ever been confused by this judging by the comment but if anyone is I really liked this video https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:foundation-algebra/x2f8bb11595b61c86:division-zero/v/why-dividing-by-zero-is-undefined

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Math Central
mathcentral.uregina.ca › qq › database › qq.02.06 › evan1.html
1/infinity and 1/0
Question: I was thinking the other day when i was in math class that when you divide 1 by say n you'll get 1/n. As the value of n increases the smaller the number you get. So if you divide 1/infinity would that equal zero? And if that is true then would 1/0=infinity be true also · Your observation ...
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Reddit
reddit.com › r/learnmath › why does 1/infinity = 0 rather than 0.0 repeating leading to 1?
r/learnmath on Reddit: why does 1/infinity = 0 rather than 0.0 repeating leading to 1?
June 3, 2024 -

sorry if the question doesnt make sense i havent been invested in math theory for long as ive only taken alg 2 and minor precalc but why is it that one over infinity equals zero rather than an infinitely small finite number? from my thoughts i feel as if it cant be zero because if you have anumerator there is a value no matter the size of a denominator, almost like an asymptotic relationship with the value reaching closer to zero but never hitting it. i understand zero is a concept so you cant operate with it so you cant exactly create a proof algebraicly but then how could you know it equals zero? just need second thoughts as its a comment debate between me and my brother. many thanks!

edit: my bad i wasnt very misunderstood on alot of things and the question was pretty dumb in hindsight, my apologies

Top answer
1 of 35
108
If the zeros are repeating there is no end, therefore there is no 1 at the end because there is no end to begin with
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Part of the problem is that 1/infinity is actually very hard to define, because "let's treat infinity as a number!" usually leads to strange situations. Like for example, what's infinity + 1? Is it still infinity? Does that mean, if we "subtract infinity" from both sides, that 1 = 0? What is infinity - infinity, anyway? One way people get around this is to use limits. Say, instead of 1 / infinity, you have 1/x. This is a function. Then we might (depending on the function) be able to ask, "what happens as we keep increasing the value of x?" People phrase this sometimes as "what happens when x 'goes to infinity'?", but what they really mean is, "what happens when we make x an arbitrarily large number, and then an even larger one, and so on?" Then people ask, "as x gets larger and larger, does the value of 1/x approach anything in particular? Does it become closer and closer to some exact value? Does it converge?" Answering this kind of question is actually much more doable than trying to figure out "what is 1 / infinity?" because, instead of having to figure out how to do division by infinity (something which does not really have a concrete definition), we're just dealing with a finite number, x. To answer the question though, what we see as x gets bigger and bigger is that 1/x does actually converge on one specific value! That value is 0. Note that 1/x is never actually equal to 0 — it just approaches it. It gets closer, and closer, and closer. People do sometimes write this as "1 / infinity = 0". But I think it would be fair to say that, when people write it this way, that can be... very misleading, depending on the reader.
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Quora
quora.com › If-1-0-is-infinity-then-what-is-1-0
If 1/0 is infinity then what is -1/0? - Quora
Answer (1 of 11): If you define some number structure where 1/0 = ∞, then, if it’s going to be as nicely behaved as possible, -1/0 = ∞ too. Shouldn’t it be -∞? Yes, it should—but -∞ should equal ∞, if ∞ is defined as 1/0. Think ...
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Quora
quora.com › Why-do-some-people-say-that-1-0-is-undefined-while-other-people-say-it-is-infinity-Which-side-of-this-endless-debate-is-right
Why do some people say that 1/0 is undefined while other people say it is infinity? Which side of this endless debate is right? - Quora
In the reals, it’s undefined for the simple reason that there are no infinite reals, and obviously there’s no finite number big enough to be 1/0. But there’s nothing illegal about talking about different kinds of numbers.
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Medium
prabhatmahato.medium.com › why-is-any-number-over-0-undefined-or-what-we-say-infinity-5318dc5b0153
Why is any number over 0 undefined or what we say infinity? | by Prabhat Mahato | Medium
March 31, 2023 - So, when the value of denominator tends to or equals to zero, then the value of the expression tends to or becomes so large that we cannot find it’s bound or in others it becomes infinity i.e., 1/0=∞.
Find elsewhere
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Wikipedia
en.wikipedia.org › wiki › Zero_one_infinity_rule
Zero one infinity rule - Wikipedia
December 1, 2024 - The Zero one infinity (ZOI) rule is a rule of thumb in software design proposed by early computing pioneer Willem van der Poel. It argues that arbitrary limits on the number of instances of a particular type of data or structure should not be allowed. Instead, an entity should either be forbidden ...
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Wikipedia
en.wikipedia.org › wiki › Division_by_zero
Division by zero - Wikipedia
1 week ago - Since any number multiplied by 0 is 0, the expression ⁠ ... Calculus studies the behavior of functions in the limit as their input tends to some value. When a real function can be expressed as a fraction whose denominator tends to zero, the output of the function becomes arbitrarily large, and is said to "tend to infinity", a type of mathematical singularity.
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Physics Forums
physicsforums.com › mathematics › general math
Disputing 1 / 0 = Infinity: Agree or Disagree? • Physics Forums
January 11, 2024 - There are an infinite amount of zero's that can go into 1, therefore we can say 1 / 0 = infinity, but it is useless to say that because infinity isn't a number. That is why we say the answer is undefined.
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Physics Forums
physicsforums.com › mathematics › calculus
Why 1 / ∞ = 0 but ∞ * 0 is not equal to 1? • Physics Forums
December 20, 2021 - The discussion also reflects varying ... = c, then a = b*c and b = a/c Therefore if 1/ ∞ = 0, ∞ * 0 should be equal to 1 and 1/0 = ∞...
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Justin Skycak
justinmath.com › undefined-versus-infinity
Q&A: Undefined versus Infinity - Justin Skycak
December 2, 2023 - Sure, if you consider 1/something, where “something” is a tiny positive number, then 1/something approaches infinity as “something” approaches 0. But that’s not the same as 1/0. That’s the limit of 1/x as x approaches 0 from the positive side.
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Quora
quora.com › Does-0-*-infinity-1
Does 0 * infinity =1? - Quora
Answer (1 of 6): Well , 0*(infinity) is indeterminate simply by definition. Infinity is a tricky expression and needs to be handled carefully. See Indeterminate -- from Wolfram MathWorld.
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Quora
quora.com › Is-1-infinity-equal-to-0
Is 1/infinity equal to 0? - Quora
Answer (1 of 94): Not immediately, no. It is equal to an unknown, infinitesimally decimated integer, the resolution and granularity of which depend upon the context and concepts involved. That said, zero doesn't mean, “nothing”, it means, “none”, which means, “not one”. So zero can easily be use...
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MathsisFun
mathsisfun.com › calculus › limits-infinity.html
Limits to Infinity
The simplest reason is that Infinity is not a number, it is an idea. So 1 ∞ is a bit like saying 1 beauty or 1 tall . Maybe we could say that 1 ∞ = 0, ...
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Medium
medium.com › @marktdodds › the-perplexity-of-infinity-and-zero-309f6bd07573
∞⁰ = ∞, 1, or undefined. Which is it? | by Mark Dodds | Medium
September 8, 2018 - So 1+2+3=1+3+2, you can but the terms in any order and the answer will still always be 6. I use this property to prove the above equation in my other article, but · forceOfHabit brought up an interesting point, does this hold for an infinite set of numbers?
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Wikipedia
en.wikipedia.org › wiki › Division_by_infinity
Division by infinity - Wikipedia
January 6, 2026 - Also, in some calculators such as the TI-Nspire, 1 divided by infinity can be evaluated as 0.