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/sci/ - Science & Math

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4449840 No.4449840 [Reply] [Original]

Hey /sci/, I've had a math question for a while now although I'm pretty fucking stupid with math so bear with me if this is pretty fucking basic.
Is .9 repeating (.999 going infinitely) equal to 1? It seems so, because 1/3 is equal to .3 repeating, 2/3 is .6 repeating, so 3/3 must be .9 repeating, but also a whole because it is 3/3. Is there any mathematical explanation for this?

>> No.4449850

OK, a few things:

Yes it is.

There are excellent proofs.

This is not wikipedia. Go there and don't post until you've read it.
http://en.wikipedia.org/wiki/0.999......

>> No.4449852

We had a huge ass discussion about this last night.

There are several proofs for this. Yours is one of them, but I would consider it the weakest .

.99999... equals one.

>> No.4449853

Look up infinite series and then sum of geometric series. Taking basic math would help.

I'm so trolled blah blah blah.

>> No.4449859

prove it by geometric convergence

>> No.4449860
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4449860

What the fuck. We literally had this thread yesterday.

At least space it out a little.

>> No.4449866

>>4449860
Sorry, I don't frequent /sci/

>> No.4449869

the basic point is that decimals are an imperfect way of representing numbers.

but people think decimals ARE numbers so freak the fuck out

>> No.4449878

Guys, do you remember when /sci/ was new?
We had 0.999... threads continuously back to back all day e'rry day for several weeks straight.

>> No.4449885

In the current, widely-accepted mathematical model, between two real numbers, there exists an infinite amount of numbers. If .999repeating were a number not equal to 1, then there would exist numbers between the two. However, .999repeating is defined in such a way that there isn't a number between it and 1.

>> No.4450056

>>4449840
Thanks, doc.

>> No.4450148

>>4449885
First time I've heard this....and I like it.

>> No.4450458

>>4449885
>circular reasoning

In saying there is no number between, you already assume they are equal.
This is not the case.

>> No.4450503
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4450503

Think of it as this:

Infinity is reachable. As you keep adding 9's the difference to 1.0 gets smaller. At infinity this difference is 1/inf = 0

>> No.4450524

>>4449840
It is.

For the love of god get off sci until you've established this though, 0.9...!=1 is a common thread here
>>4449860
Wait, you think this is a recent thing? /sci/ has been doing this since it started.