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-   -   Math question (maybe our resident rocket scientist can help) (http://archives2.twoplustwo.com/showthread.php?t=185619)

elwoodblues 01-28-2005 12:46 PM

Math question (maybe our resident rocket scientist can help)
 
This has always bothered me. I think it is just trying to wrap your head around infinity, but any help from anyone would be appreciated.

Does .999999(repeating) really = 1? I think it's just really, really (repeating) close, but the below suggests otherwise:

1/9 = .11111(repeating)
1/9 x 9 = 1
.11111(repeating) x 9 = .99999(repeating)
Therefore .99999(repeating) = 1

ThaSaltCracka 01-28-2005 12:49 PM

Re: Math question (maybe our resident rocket scientist can help)
 
I think a really anal math teacher will tell you .9999999 does not actually equal one.

Tron 01-28-2005 12:50 PM

Re: Math question (maybe our resident rocket scientist can help)
 
They are just different ways of writing the same thing.

GuyOnTilt 01-28-2005 12:52 PM

Re: Math question (maybe our resident rocket scientist can help)
 
Any middle school level math text would be able to tell you this. I'm sure you've read it in reliable sources before, so why are you still asking? The answer is still yes.

GoT

Mano 01-28-2005 12:54 PM

Re: Math question (maybe our resident rocket scientist can help)
 
That is correct, there is no difference between .9999... and 1 ( i.e. 1 - .9999... = 0).

elwoodblues 01-28-2005 12:56 PM

Re: Math question (maybe our resident rocket scientist can help)
 
[ QUOTE ]
I'm sure you've read it in reliable sources before, so why are you still asking? The answer is still yes.


[/ QUOTE ]

I "know" the answer is yes because people have told me and I can "prove." I just have a hard time wrapping my head around it. My mind tells me that they aren't equal and that they have a difference of .0000(repeating)1.

TimM 01-28-2005 01:00 PM

Re: Math question (maybe our resident rocket scientist can help)
 
[ QUOTE ]
I "know" the answer is yes because people have told me and I can "prove." I just have a hard time wrapping my head around it. My mind tells me that they aren't equal and that they have a difference of .0000(repeating)1.

[/ QUOTE ]

The repeating zeros are infinite in number, so you never get the 1.

junkmail3 01-28-2005 01:53 PM

Re: Math question (maybe our resident rocket scientist can help)
 
[ QUOTE ]
[ QUOTE ]
I "know" the answer is yes because people have told me and I can "prove." I just have a hard time wrapping my head around it. My mind tells me that they aren't equal and that they have a difference of .0000(repeating)1.

[/ QUOTE ]

The repeating zeros are infinite in number, so you never get the 1.

[/ QUOTE ]

This is correct. Otherwise, what would be the point of haveing a number that is .9999999999999999... and a number that is 1.

if they are the same thing, call them the same thing. You will approach 1 (and for many applications can call it one) but it is not turely 1. Ever.

anisotropy 01-28-2005 03:13 PM

Re: Math question (maybe our resident rocket scientist can help)
 
[ QUOTE ]
1/9 = .11111(repeating)

[/ QUOTE ]
incorrect. The decimal form is an approximation of an irregular number.
[ QUOTE ]
1/9 x 9 = 1

[/ QUOTE ]
correct
[ QUOTE ]
.11111(repeating) x 9 = .99999(repeating)

[/ QUOTE ]
correct
[ QUOTE ]
Therefore .99999(repeating) = 1

[/ QUOTE ]
incorrect

BeerMoney 01-28-2005 03:32 PM

Re: Math question (maybe our resident rocket scientist can help)
 

Let
n=.9999999999999999...
10n=9.9999999999999999.....
10n-n = 9
9n = 9
n = 1

It is wierd. I guess our number system is messed up.


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