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0.999...= 1

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Re: 0.999...= 1

#51
post #40

Earlier quoted context omitted.

or, x = 0.9999... 10x = 9.999... 10x = 9 + 0.999... 10x = 9 + x 9x = 9 x = 1 Presented slightly more clearly https://en.wikipedia.org/wiki/0.999...#Algebraic_arguments

Yeah that’s way more complicated than it needs to be and I’m tempted to replace that whole section with: x = 0.9999... 2x = 1.9999... 2x - x = 1 x = 1

How do you jump from

x = 0.999...

to

2x = 1.999..

Re: 0.999...= 1

#52
post #37

This can be solved by using base 12 rather than base 10 to do the calculation...

Firm believer that adopting base 12 would have had a ripple affect on society, preventing many trials tribulations and wars. Pity we only have base 10 and donald trump

base 12? Them are fighting words...I call WAR!

Re: 0.999...= 1

#53
post #9

I remember being doubtful when being presented with this in middle school, but after being shown this as fractions makes it obvious: 1/3 = 0.333.. 3 * 1/3 = 3 * 0.333.. 3/3 = 0.999.. 1 = 0.999..

Nice to see a few different proofs/intuitions here. Not being a big fan of symbol manipulation, I always felt partial to the proof/intuition that you couldn't find another number between the two :-)

Re: 0.999...= 1

#54

I remember WarCraft 3 official forums being torn apart by this, with probably thousands of comments in the thread. Blizzard even had to post their official stance on the issue, but that didn't calm those who insisted 0.999... was 1 minus epsilon and not exactly 1.

I'm glad someone else remembers this. To this day, whenever I see 0.999... = 1, I think of the Battle.net forums inexplicably flooded with threads about it for what felt like ages.

Re: 0.999...= 1

#55

I'll just chime in with my completely ignorant theory that 1 - 0.999... = the infinitely smallest number, but is still, in my mind, regardless of any logic, reason, or educated calculations, greater than 0. I understand and accept this is wrong. However, somewhere in my brain I still believe it. Sort of like +0 and -0, which are also different in my head.

Philosophically you are right.

Mathematically you are wrong.

It is indeed true that if there was an entity that could reason beyond infinity 1-0.999... would be greater than 0.

Re: 0.999...= 1

#56

Maybe the major source of confusion is that our decimal representation for whole numbers is supposed to be unique. Then when we extend it to rationals and reals this property fails at rationals in the form of a/10^n. Arguably the sign symbol ruins it for whole numbers as well, as +0 and -0 could be equally valid representations of the number 0. We just conventionally don't allow -0 as a representation. There are othe…

I don’t know, I don’t recall students having much trouble accepting that 1 = 1.0 = 1.000.

Re: 0.999...= 1

#57
post #9

I remember being doubtful when being presented with this in middle school, but after being shown this as fractions makes it obvious: 1/3 = 0.333.. 3 * 1/3 = 3 * 0.333.. 3/3 = 0.999.. 1 = 0.999..

This also happens to be the test for whether your calculator is any good.

Re: 0.999...= 1

#58
post #52

Earlier quoted context omitted.

Firm believer that adopting base 12 would have had a ripple affect on society, preventing many trials tribulations and wars. Pity we only have base 10 and donald trump

base 12? Them are fighting words...I call WAR!

We haven't even started the Pi Tau argument yet

Re: 0.999...= 1

#59

This is 'more intuitive' if you think about it this way: If any two real numbers are not equal, then you can take the average and get a third number that is half way between them. Conversely, if the average of two numbers is equal to either of the numbers, then the two numbers are equal. (this isn't a proof, just a way to convince yourself of this) What's the average of .9999... and 1?

0.999…5 obviously.

But at which position that "5" is? Tell the number please.
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