Poll: 0.999... = 1

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Fraught

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This is SO old that I think someone making another thread about it made me puke into my mouth a bit.
 

emeraldrafael

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havass said:
emeraldrafael said:
havass said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Ah, but I haven't stated whether I think they equal or not. I only proved it. I don't put my faith in the proof, but every step seems logical enough on the basic level.
Well, I stated why i dont believe that in a post that was buried in the thread earlier, as you using two separate X values, not the same X value for the same problem. When you said implying, that was a separate math problem and you found a different value.

Rabid Toilet said:
emeraldrafael said:
Rabid Toilet said:
actually 9(.999) = 8.991 rounded, thats 9
I assumed that he meant to write .999..., rather than just .999.
Either way, you're still getting the same number, which yes, rounds up to 9, but this is a thread about not rounding up and more about perfect equaling.
 

BENZOOKA

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Rubashov said:
benzooka said:
0.999... is not 1
It is as simple as that. No matter how you twist and try to prove it.
WolframAlpha disagrees:

http://www.wolframalpha.com/input/?i=summation%289%2F%2810^n%29%29+from+n+%3D+1+to+infinity

Its unproven assertions are probably at least as reliable as yours. :)
I already fixed my inadequate assertion in this [http://www.escapistmagazine.com/forums/read/18.252127-Poll-0-999-1?page=4#9363044] reply.
 

Coldie

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This thread is highly amusing. It's like mathematical schadenfreude!

emeraldrafael said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Yes, just like 5/5, 75-74, and 0.2 * 5 are three separate numbers.

Shadowkire said:
LOL, I totally didn't realize that, you are correct in that it DOES NOT MATTER:
x = 0.999... is an assumption, one that requires proof, the fact that the proof ends as 0.999... = 1 means that the assumption is wrong
'x = 0.999...' is not an assumption, it's a definition. A definition does not require proof, as it is always right, by, uhm, definition. The assumption was '1 = 0.(9)' and it was reached legally from a true statement. QED.
 

Shadowkire

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havass said:
Shadowkire said:
The argument over the proof
Actually, I have no faith in that proof. I was just getting you back for saying I failed at math. I couldn't care less if 0.99999.... = 1, the difference is so inconsequential that the only problem you'll have is when dealing with log functions. And even then it's still a very small difference.
I apologize, it was wrong of me to say you failed at math, I didn't intend to offend you.
 

Rabid Toilet

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tthor said:
BlacklightVirus said:
havass said:
If x = 0.999999...
Then 10x = 9.9999...
Therefore, 10x - x = 9
Which implies 9x = 9
Thus, x = 1
x also = 0.99999...

In conclusion, I have just proven 1 = 0.9999...
I prefer:

b0.b1b2b3b4... = b0 + b1(1/10) + b2(1/10)^2 + b3(1/10)^3 + b4(1/10)^4 ...

if |r| < 1 then kr + kr^2 + kr^3 + ... = kr/(1-r)

So for 0.9...:

0.(9) = 9(1/10) + 9(1/10)^2 + 9(1/10)^3 + ... = (9(1/10))/(1-(1/10)) = 1
... you know what, I'm just gonna chalk this down to <link=http://en.wikipedia.org/wiki/Proof_by_intimidation>Proof by intimidation
The notation is kind of hard to get across in text, since there's a lot of subscripts and superscripts involved.

He's modeling the number .99... as a geometric series (basically .9 + .09 + .009 ...). Given what we know about these series, the sum of all of the numbers in the series (which would equal .99...) is equal to the first number (9/10 = .9) over 1 minus the number it's being multiplied by to the power of its place in the series (the first place is zero) ((9/10) * (1/10) ^ 0 , (9/10) * (1/10) ^ 1 , (9/10) * (1/10) ^ 2 , etc.).

Thus, the sum of all the numbers in the series equals the fraction (9/10) divided by (1 - (1/10)), or (9/10) divided by (9/10), which is 1.

Not sure if that explains it any better or if it just made it more confusing, but the math is sound, and it does indeed prove that .99... = 1.
 

emeraldrafael

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Coldie said:
emeraldrafael said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Yes, just like 5/5, 75-74, and 0.2 * 5 are three separate numbers.
No, they're all numbers with the same equivical value. each = 1. But .999 =/= 1.

The easiest way to put is this. Say you had... um... oka, I'm going ot have to change the numbers a bit, but it will stil be the same.

Say you had $9.99. and in this perfect world that you will live in for sake of argument, everything costs exactly has advertised (no tax). So an item is $10. You're 9.99 does not equal the 10, so you do not get what you wanted to be (a DVD lets say just to make it realistic). 0.999..... =/= 1 in much the same way.
 

acer840

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havass said:
If x = 0.999999...
Then 10x = 9.9999...
Therefore, 10x - x = 9
Which implies 9x = 9
Thus, x = 1
x also = 0.99999...

In conclusion, I have just proven 1 = 0.9999...
Well, the algebra equation is incorrect:

If x = 0.99999*
Then 10x = 9.99999*
Therefore 10x - x = 9x
Which implies 9x = 8.99999*
Thus x = 0.99999*

In conclusion, I have just proven 1x = 0.99999*
 

Shadowkire

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Coldie said:
This thread is highly amusing. It's like mathematical schadenfreude!

emeraldrafael said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Yes, just like 5/5, 75-74, and 0.2 * 5 are three separate numbers.

Shadowkire said:
LOL, I totally didn't realize that, you are correct in that it DOES NOT MATTER:
x = 0.999... is an assumption, one that requires proof, the fact that the proof ends as 0.999... = 1 means that the assumption is wrong
'x = 0.999...' is not an assumption, it's a definition. A definition does not require proof, as it is always right, by, uhm, definition. The assumption was '1 = 0.(9)' and it was reached legally from a true statement. QED.
You apparently have no idea how logic/mathematical proofs work so here I go:
claiming x=0.999... is an assumption, 1=0.999... is what he intended to prove.
the reason his proof is wrong is because he failed to prove the assumption.

Understanding it requires college level math.
 

Rabid Toilet

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emeraldrafael said:
havass said:
emeraldrafael said:
havass said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Ah, but I haven't stated whether I think they equal or not. I only proved it. I don't put my faith in the proof, but every step seems logical enough on the basic level.
Well, I stated why i dont believe that in a post that was buried in the thread earlier, as you using two separate X values, not the same X value for the same problem. When you said implying, that was a separate math problem and you found a different value.

Rabid Toilet said:
emeraldrafael said:
Rabid Toilet said:
actually 9(.999) = 8.991 rounded, thats 9
I assumed that he meant to write .999..., rather than just .999.
Either way, you're still getting the same number, which yes, rounds up to 8, but this is a thread about not rounding up and more about perfect equaling.
I won't bother replying to the second point, since I'm not even sure what the original point was.

As to your first point, where you assert that there were two different equations in his proof? That is false.

You said that 10x - x = 9 and 9x = 9 were two different equations. What is 10x - x? If you have 10 "x"es and you take one away, you get 9 "x"es.
 

emeraldrafael

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Rabid Toilet said:
emeraldrafael said:
havass said:
emeraldrafael said:
havass said:
I think what they are getting at is yes, it does wind down to equaling .999=1 but .999=/=1 as they are two separate numbers.
Ah, but I haven't stated whether I think they equal or not. I only proved it. I don't put my faith in the proof, but every step seems logical enough on the basic level.
Well, I stated why i dont believe that in a post that was buried in the thread earlier, as you using two separate X values, not the same X value for the same problem. When you said implying, that was a separate math problem and you found a different value.

Rabid Toilet said:
emeraldrafael said:
Rabid Toilet said:
actually 9(.999) = 8.991 rounded, thats 9
I assumed that he meant to write .999..., rather than just .999.
Either way, you're still getting the same number, which yes, rounds up to 8, but this is a thread about not rounding up and more about perfect equaling.
I won't bother replying to the second point, since I'm not even sure what the original point was.

As to your first point, where you assert that there were two different equations in his proof? That is false.

You said that 10x - x = 9 and 9x = 9 were two different equations. What is 10x - x? If you have 10 "x"es and you take one away, you get 9 "x"es.
Damn, that should have been a nine instead of an eight when it rounds up.

he said it Implies. he's changing the equation and the value of X. X as variable can not hold the same value. and again, if you want to prove it, look into the concept of graphical limits.
 

Rabid Toilet

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acer840 said:
havass said:
If x = 0.999999...
Then 10x = 9.9999...
Therefore, 10x - x = 9
Which implies 9x = 9
Thus, x = 1
x also = 0.99999...

In conclusion, I have just proven 1 = 0.9999...
Well, the algebra equation is incorrect:

If x = 0.99999*
Then 10x = 9.99999*
Therefore 10x - x = 9x
Which implies 9x = 8.99999*
Thus x = 0.99999*

In conclusion, I have just proven 1x = 0.99999*
I honestly have no idea what you did there, but your algebra is most certainly not correct.

If x = 0.99999* (Right so far)
Then 10x = 9.99999* (Still good)
Therefore 10x - x = 9x (What? How does 9.99* - x = 9x?)
Which implies 9x = 8.99999* (And how does 9x = 8.999*?)
Thus x = 0.99999* (Did you divide both sides by 9? If so, how did you get that 8.99*/9 = .99* unless you assumed that .99* = 1?)
 

Lyx

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Hail Fire 998 said:
The original argument was, that both are equal *without* rounding.
Ah.
I think I'd say yes.
For practical purposes, yes - in practice, there will never be a significant difference between both.
The reason for this is that in practice, we can never do something infinitely accurate. Let's say, we want to bring the temperature of a can with water to 1 degrees celsius. The water will never be "exactly" 1 degrees anyways, so the difference between 0.999999999... and 1 really makes no practical difference (because our accuracy at regulating the water temp is lower, than the difference).

In theory, there is however a difference between both.

Many people think of infinity as a number. But it isn't really a number. Rather, it is a loop... for example, for 0.999... what it does is this:

Step 1: add another 9 at the end
Step 2: go to step 1

So, it is more like a command "do this over and over forever".

They keyword is "forever".... this "task" will never finish, because it has no end (it's a loop).

When infinity is used for practical purposes, for example, in a computer program, they just let the above loop run for a while, until there are enough 9's to be satisfied with the accuracy..... for example, they may say "stop when it reaches 9 digits after the comma".

0.999999999

Thats not infinity, because the loop didn't run forever :)
 

havass

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Shadowkire said:
havass said:
Shadowkire said:
The argument over the proof
Actually, I have no faith in that proof. I was just getting you back for saying I failed at math. I couldn't care less if 0.99999.... = 1, the difference is so inconsequential that the only problem you'll have is when dealing with log functions. And even then it's still a very small difference.
I apologize, it was wrong of me to say you failed at math, I didn't intend to offend you.
No offence taken, I just like having a good logical argument once in a while. Heheh.
 

Rabid Toilet

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emeraldrafael said:
Damn, that should have been a nine instead of an eight when it rounds up.

he said it Implies. he's changing the equation and the value of X. X as variable can not hold the same value. and again, if you want to prove it, look into the concept of graphical limits.
He shouldn't have used the word "implies", but it doesn't change the fact that it's the same equation.
 

Coldie

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emeraldrafael said:
Say you had $9.99. and in this perfect world that you will live in for sake of argument, everything costs exactly has advertised (no tax). So an item is $10. You're 9.99 does not equal the 10, so you do not get what you wanted to be (a DVD lets say just to make it realistic). 0.999..... =/= 1 in much the same way.
I cannot even begin to comprehend how you have reached '0.999... != 1' from '9.99 != 10'. 0.(9) does equal 1. 9.99 does not equal 10. The only common theme is that here there be nines.

The only argument you could have here is that numbers 0.(x) are a canonical representation of periodic numbers, where x is the repeating pattern, so 0.(9) and 1 are different canon forms and therefore are different numbers. However, since 0.(9) and 1 both represent the same value, (9) notation is expressly forbidden. Thus x cannot be 9 (or consist only of nines, i.e. 99, 999, for obvious reasons) and 0.(9) is a non-canon form of 1.
 

Jelly ^.^

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This is why I wish more people would support my idea to introduce a base-12 numerical system :(
 

havass

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emeraldrafael said:
Damn, that should have been a nine instead of an eight when it rounds up.

he said it Implies. he's changing the equation and the value of X. X as variable can not hold the same value. and again, if you want to prove it, look into the concept of graphical limits.
Uh..please don't use my choice of word in the argument. I was just putting in random words to continue with my equation. I didn't really think about the word I was using. >.>