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Does 0.9999 repeating 9 equal 1?


greenspandan

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This isn't a debate. This is just some people who are unable to learn.

There are also people who are unable to see over the other side of the fence. ;) Within the context of mathematics, you guys are right. Your proofs are outstanding but I do think there's the danger of arrogance when people don't acknowledge the limits of mathematics. There's a small but growing group of people that are unhappy in the way mathematics has dominated astrophysics and the increasing number of ad-hoc theories to explain the universe. That's what this thread reminded me of.

I find it fascinating that the proofs given goes against most of our instincts. If you can't appreciate the people struggling with the concept of an infinite number of 9s then you probably lost of a bit of that intellectual inquisitiveness of why things are and the instrument of math as a utility in order to better understand the world.

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WOW. Hallelujah.

And here I was with a post all queued up about the notion that the infinitely long expression "1 * 1 * 1 *..." is merely a concept that can't be evaluated to a real number.

Happy to ditch that for this outcome instead. :)

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...I find it fascinating that the proofs given goes against most of our instincts. If you can't appreciate the people struggling with the concept of an infinite number of 9s then you probably lost of a bit of that intellectual inquisitiveness of why things are and the instrument of math as a utility in order to better understand the world.
I can appreciate it, especially since I was one of the ones that struggled ... but it only took me one or two posts to see it. Besides, I already knew about .333... being a third... so it was pretty easy for me.

450 posts and 36 proofs .... that's a diff story

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I can appreciate it, especially since I was one of the ones that struggled ... but it only took me one or two posts to see it. Besides, I already knew about .333... being a third... so it was pretty easy for me.

450 posts and 36 proofs .... that's a diff story

Did you really go back and count? If so, touche!

Also, were those 36 different proofs?

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Did you really go back and count? If so, touche!

Also, were those 36 different proofs?

No. Probably three or four actual proofs - plus a link to a half dozen scientists from one site each explaining it in a half dozen different ways. And maybe another dozen explanations from different sites, plus at least a couple dozen explanations in this thread.
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No. Probably three or four actual proofs - plus a link to a half dozen scientists from one site each explaining it in a half dozen different ways. And maybe another dozen explanations from different sites, plus at least a couple dozen explanations in this thread.

Geez, that's it?

How is someone supposed to understand with so little backing?

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There are also people who are unable to see over the other side of the fence. ;) Within the context of mathematics, you guys are right. Your proofs are outstanding but I do think there's the danger of arrogance when people don't acknowledge the limits of mathematics. There's a small but growing group of people that are unhappy in the way mathematics has dominated astrophysics and the increasing number of ad-hoc theories to explain the universe. That's what this thread reminded me of.

Sorry. Feel an overpowering urge to put this in this thread.

Doonesb.gif

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I get it because 1/3 = 0.333... by definition. Even though it is counter intuitive to me that the number 0.333... will have infinite number of 3's and will never end, yet we have defined this as the expression 1/3. This is why I got stuck on the concept of 1/(infinity)... it's a non-zero number so small it cannot be quantified; yet it is not zero (yet it is equal to zero!).

It's confusing to mix the concept of infinity, as in an expression of a number so large it cannot be quantifiable, then take infinity and say "this expression is 0.999... with an unquantifably large numbers of 9's at the end".

Then, take that 0.999... expression and say "it is 1". No, the expression is not 1. However; it is "equal to" 1, since 0.333... is *defined to be* 0.333 with infinite number of 3's. In my mind I still want to say there is a difference between 1/3 and 0.333... and that difference is 1/(infinity); of course this is a number so small it is unquantifiable.

Trying to work with infinity just messes with my head.

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I get it because 1/3 = 0.333... by definition. Even though it is counter intuitive to me that the number 0.333... will have infinite number of 3's and will never end, yet we have defined this as the expression 1/3. This is why I got stuck on the concept of 1/(infinity)... it's a non-zero number so small it cannot be quantified; yet it is not zero (yet it is equal to zero!).

It's confusing to mix the concept of infinity, as in an expression of a number so large it cannot be quantifiable, then take infinity and say "this expression is 0.999... with an unquantifably large numbers of 9's at the end".

Then, take that 0.999... expression and say "it is 1". No, the expression is not 1. However; it is "equal to" 1, since 0.333... is *defined to be* 0.333 with infinite number of 3's. In my mind I still want to say there is a difference between 1/3 and 0.333... and that difference is 1/(infinity); of course this is a number so small it is unquantifiable.

Trying to work with infinity just messes with my head.

You're thinking too much.

.333... is one third. You should be able to "see" it, without worrying about all the infinity crap. If you don't quite get the infinity stuff, it doesn't matter, because you can SEE it.

I believe you do see it now.

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ooh, ooh, I have a question!

lets say, hypothetically, that a hockey goalie has 9 save on 10 shots. his save percentage is .900. Now, lets say that his number of shots increases to infinity and he saves every single one of those shots. what is his save percentage?

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Or how about this one:

Someone asks a mathematical question on ES. A poster in that thread choses to re-define the question in such a way that he comes up with an answer that isn't correct (by answering a different question than the one that was asked.)

If, as the length of the thread approaches infinity, the poster continues to come up with more and more ways of changing the question that was asked into a different question where his answer becomes correct, and if people keep pointing out that he's changing the question, and he keeps ignoring them and changing the question yet again, and if he never gets tired of changing the question, then will his answer ever equal "correct"?

:)

The question is "Does .9 repeating . . . ".

Not "Does a series of 9's, starting with a single 9, and then growing to add more 9's, and more and more, and continuing to grow in the direction of infinite length . . . "

In fact, let me point something out about your attempts to rephrase the question:

The question is "Does .9 repeating . . "

And what you keep trying to change it into is "Does a number which approaches .9 repeating . . . "

You're not giving examples of series that approach 1. You're giving examples of series which approach .9 repeating. In short, of series which approach the place where the number in the question already is.

You can't even rephrase the question without admitting (at least philosophically) that the answer to the original question is "yes".

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ooh, ooh, I have a question!

lets say, hypothetically, that a hockey goalie has 9 save on 10 shots. his save percentage is .900. Now, lets say that his number of shots increases to infinity and he saves every single one of those shots. what is his save percentage?

that bears no resemblence to 0.9 repeating 9, which is a fixed value, not one that is growing over time.

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  • 2 years later...
ooh, ooh, I have a question!

lets say, hypothetically, that a hockey goalie has 9 save on 10 shots. his save percentage is .900. Now, lets say that his number of shots increases to infinity and he saves every single one of those shots. what is his save percentage?

99.9999999999999999999999...%, but NOT 100%, since he still missed one.
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