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Hmm...


Ash-Kennard

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those of you that do maths or physics or have any brain power will know that 1 doesn't equal 0.999* (* = recurring) with no rounding

someone in my physics class brought this up today...

x = 0.999*

10x = 9.999*

10x - x = 9.999* - 0.999*

9x = 9

0.999* = 1

discuss

edited...

Edited by Ash-Kennard
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9.999* is theoretical, it isn't a number.

When you times it by ten, your just shifting the decimal one way. Making the number which went on for infinite, to infinite +1. That isn't taken into consideration when you did the math.

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10x doesnt equal 9.9999 recurring - thats the easy answer ... in my opinion anyway - at infinity as the nines stretch away there has to be a zero at the end compared to the 0.999999 recurring - which accounts for your lost .0000000000000000000000000000000000000000000000000000000000000000000000000000000

00000000000000000000........00000000000001 .... I guess there are arguments for and against.

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anyway mathematicians have argued over this for years so we're not going to solve it on here.

My understanding is that they haven't argued about it for years. They all agree that 0.999... == 1

It's really about what you think of as 'infinity'. 0.999... streches to infinity and is therefore infinitely close to 1. It's not intuitive for us to think that 0.999... might equal 1, but unless you can come up with a counter-proof to what ash posted, you don't have a leg to stand on.

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0.9999* = 0.9999*, its quite simple. I just did that with absolutely no working out at all. Proof that it doesn't equal one.

Theres quite a geeky saying that "2+2=5, for very large values of 2, or small values of 5". Sometimes happens on computers if you do not allow enough.. significant digits (?) in memory - but totally irrelevant to this topic.

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When you times it by ten, your just shifting the decimal one way. Making the number which went on for infinite, to infinite +1. That isn't taken into consideration when you did the math.
That's precisely the point of the proof though!

What is infinity minus 1? Or infinity plus 1?

(the answer in both cases is infinity)

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Exactly.

0.999 recurring (to infinity) minus the last '9' in the series is still an infinitely long string of 9s. Hence this bit makes perfect sense.

10x = 9.999*

10x - x = 9.999* - 0.999*

I might not have explained that very well, but suffice it to say, the proof is sound.

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0.99999999999999999999999999999999999999999

If your a mathmatition - no, its not one

If your an engineer - its near enough

According to my maths teacher who is a professor of engineering.

mathmatitions say .999 recurring does equal 1. theres the arithmetic series which shows proof, and probably integration aswell

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mathmatitions say .999 recurring does equal 1. theres the arithmetic series which shows proof, and probably integration aswell

Yes, that's what this topic's about :mellow:

Anyway, 0.999999999999999999999999 is not the same as 0.999...

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Yes, that's what this topic's about :mellow:

Anyway, 0.999999999999999999999999 is not the same as 0.999...

but i quoted someone who said mathmatition say 1 is not the same as 0.9999recurring

if you only say 3 decimal places, such as 0.999 then its obviously a number in its own and doesnt equal 1, did i miss something here?

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