0.9 recurring equal to 1?

cata_mint

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Maybe its because I'm a...
I've just been forum drifting and I had no idea but apparently this is a Huge issue with some people. They have conversations lasting months debating it from every angle, and in the end all the uni students get really rude and start calling everyone who doesn't believe it nasty names.
I wanted to say how happy I was to be a part of a forum with such a friendly warm atmosphere, who never stoops to name calling and petty insults. \t

Its true btw.
 

zissou'smom

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Debating whether .999999999999... is equal to 1???? I can't imagine a real-life scenario in which the difference would matter.

If they are equal, then how on earth can .99... exist? Isn't it a fraction of some sort, like 1/3 or 2/3rds? I don't get math.

I doubt anyone'll fight over this. I'll be too busy hiding from the scary math and numbers.
 

lookingglass

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Why wouldn't you round up? Perhaps I don't understand the question.

Anyway.. welcome to TCS... where there are no nasty name callers.
 

katachtig

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Originally Posted by Zissou'sMom

Debating whether .999999999999... is equal to 1???? I can't imagine a real-life scenario in which the difference would matter.
There are times with computers where I have written code to say x=y and the program would return false. Depending on the precision of the numbers, 2 minus 1 would equal 0.999999999999 which always caused me grief, but I would never reach the point of calling people names over it (the computer, that is another issue).
 
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cata_mint

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I don't really get it either, I just know it is and can write a couple of proofs on it. I was mostly just astounded at the number of people who were willing to fight this to the bitter end, for hours on end without stopping, just to be right. None of them knew or cared who the others were, and none had more than 600 posts to their name, despite having been there for years. It was kinda scary



A link to the guardian's own version.
http://www.guardian.co.uk/g2/story/0,,1802873,00.html
 

zissou'smom

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Oh, I get that 1/3 x 3 must equal 1. That makes more sense.

But still, I thought that fractions and decimals couldn't really be compared?

Meh. I can't imagine anyone actually fighting about this except in an obscure office at MIT in the math building or something. I can see a healthy debate, maybe even a thesis... but an argument?

Some people just like to argue and insult and whatnot. I like to debate... but never call names or anything but a friendly debate.

That is one of the great things about this site! It is polite and friendly, rather than your run-of -the-mill full of crazies who just want a fight, regardless of what about.

That other one you were talking about with the bitter argument... I wouldn't be surprised if the most heated arguer on both sides was the same person, and a troll.
 

icklemiss21

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My answer would be who really cares about it enough in a general forum to debate it (now computer/mathematics forums are a different matter), but each to their own


I believe my prof said that 3 thirds (or 0.9 recurring) was equal to or less than 1

Welcome to TCS
 

starryeyedtiger

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AHHHHHHHHHHHHHH!!!!!!!!!! NO MATH ON TCS PLEASE!!!!!! Lol, now i'm a nervous wreck.
That stuff should really be
! lol.
 

katachtig

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Originally Posted by cata_mint

I've just been forum drifting and I had no idea but apparently this is a Huge issue with some people. They have conversations lasting months debating it from every angle, and in the end all the uni students get really rude and start calling everyone who doesn't believe it nasty names.
I wanted to say how happy I was to be a part of a forum with such a friendly warm atmosphere, who never stoops to name calling and petty insults.

Its true btw.
Originally Posted by StarryEyedTiGeR

AHHHHHHHHHHHHHH!!!!!!!!!! NO MATH ON TCS PLEASE!!!!!! Lol, now i'm a nervous wreck.
That stuff should really be
! lol.
Originally Posted by icklemiss21

It's ok Nikki, we promise never to bring it up again... unless the gnomes do it first
So did a gnome kidnap Cata_mint and post this evil math stuff?
 

icklemiss21

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Originally Posted by katachtig

So did a gnome kidnap Cata_mint and post this evil math stuff?
Who else but an evil gnome would make this poor innocent person bring up evil mathematics on a catsite

and to prove it (they have taken over Grinnell College, IA):
 

icklemiss21

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I know! It's bad, one week they are taking over gardens, then TCS and now the education system! It can only get worse from here, think about how many young minds they can infect with their evil gnomeness!
 

starryeyedtiger

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Originally Posted by icklemiss21

It's ok Nikki, we promise never to bring it up again... unless the gnomes do it first
Thankyou
I feel a little less paraniod now lol
 

annasmom

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To bring this thread back to its origins...


I'd like to see the proofs that you've written that show .999 repeating is equal to 1. It is my opinion that they are two different numbers. Now, the question is what type of calc/computer is doing the math. Perhaps a machine with thousands of characters would finally yield something other an a 9 in the series (making it less than 1 more definitively). Pi is 3.14159265358979323846, but the numbers go on indefinitely and Pi is its own number. I would never resort to name-calling over this, however.
 

jdpesz

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Now you've done it. The gnomes made me read this thread and now I have a headache!
IMHO, if .999999--- is the decimal expression of 3/3, and any fraction in which the numerator and the denominator are the same is equal to 1, than .999999--- MUST equal 1. Just in case anyone still cares.
 

mikeanderson

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This is the "proof" I've seen (see if you can spot the problem):

Let x=.999999999bar (the "forever" version)
Then, 10x=9.9999999999bar (again, with bar)
10x - x = 9x
Simultaneously...
9.999999bar - .999999bar = 9

So, you have 9x = 9, and therefore x=1

Since x is both 1 and .9999999bar, they must be equal.
 
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cata_mint

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Maybe its because I'm a...
The worst thing is though, as far as math teachers and professors etc are concerned its not even an issue. They all went through the irritating uni phase and know that its true, but so many people still argue against it even though as far as maths is concerned its an accepted fact. I almost regret starting this thread now...
 
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