Math Proof

Martin · **Posted:** Tue Sep 09, 2003 11:40 pm

I just want to know what people think about this. Please don't reply to this post just yet, only vote.

Here's the question.
Does 0.999... (repeating) = 1, or is it just really really close?

octopi · **Posted:** Wed Sep 10, 2003 12:18 am

Removed my comments

Martin · **Posted:** Wed Sep 10, 2003 3:24 pm

The not posting part was more for people who don't know the answer, so they wouldn't have anyone pushing them in either direction...

Dan · **Posted:** Wed Sep 10, 2003 4:54 pm

wow it is at 50% / 50% right now, i whonder how this one will turn out.

Martin · **Posted:** Fri Sep 12, 2003 3:52 pm

At the time of writing this the tally was:

6 said Yes
9 said Almost

Well, here's the proof.

Let x = 0.999...repeating
therefor 10x = 9.9999...repeating

10x - x = 9.999..repeating - 0.9999...repeating
therefor 9x = 9, and x = 1.

ooo ahh.

Dan · **Posted:** Fri Sep 12, 2003 4:12 pm

me and octopi talked about this for arouged about this for about 2 hours on msn. Turst me, 0.9999... != 1. To complet that math you have there you HAVE TO round if you dont it will never end, there for 0.9999... rounded is 1. that is why you are geting 1. you cant subtrace 0.9999... from 9.9999... with out rounding, it whould go on forover and you whould never get an aswer.

so to sum that up 0.9999... != 1

now let the flaming start!!!

octopi · **Posted:** Fri Sep 12, 2003 4:23 pm

Since you let

code:

_
x=0.9

You can subtract x from

code:

_
9.9

You don't need to round anything.

An easier solution is this:

code:

1/3 + 2/3 = 3/3
_ _
0.3 + 0.6 = 1
_
0.9 = 1

PaddyLong · **Posted:** Fri Sep 12, 2003 5:40 pm

no 0.9999 is not = to 1 ... consider this ...

1 / (1 - x)

now do this for x = .9repeating and x = 1

1 / (1 - .9repeating)
1 / 0.0..lots of zeros...1

1 / (1 - 1)
1 / 0 <--- not possible .... ever heard of asymtotes?

some numbers are just really really close to 1 .... but that is all... they are not equal to 1 ... 1.0000000000000000000000000000000 is different than 0.9 repeating

what you are saying is that any number n.9repeating = n+1

SilverSprite · **Posted:** Fri Sep 12, 2003 6:54 pm

0.9 repeating IS equal to 1. Darkness proved it. Another proof is using infinite geometric sums. Also octopi gave another proof. Paddylong, the wrong thing about your 'proof' is that 9 is repeating infinitely. So how can you say ther eis 0.0000000 ... 1 ???? that means you are terminating the string of 0s.

PaddyLong · **Posted:** Fri Sep 12, 2003 10:20 pm

it was not meant to be a proof just a consideration

ok, after doing some further reading on the subject, I am wrong and 0.9 repeating does = 1

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