A question of numbers (one for the maths fans)

If 1/3 of a pie is only 60 degrees, we can each have 3/3.

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Sure you can9.99etc = 9 + .99etc
0.99etc = 0 + .99etc9 - 0 = 9
.99etc - .99etc = 09 + 0 = 9

Since when is etc a number?Do me a favor, can you write out the whole number for me, so we can do the equation?Edited by riVeRraT, : No reason given.

Abbreviation for et cetera, that's Latin for "&shit"Also, what kind of pie? Which one, 10 or 1?Edited by Iblis, : autistic chat

Oh yes you can! Oh no it doesn't! Surely you mean 9? You have to subtract more than 1 to get 8.999991. If we have 9.999999... then you need to propose the number 8.9999999...1 (an infinite number of 9s followed by a 1!), which would assume infinity has an end, where a 1 is located. That's crazy talk!It's quite a provocative piece of maths, it feels very naughty don't you think? More here.

You can't subtract it long hand, one digit at a time. But what is to prevent us from subtracting all digits at once? ever heard of math recursion?

Are you planning on explaining why you posted that question?

no they are spelt differently , using .999999999 in place of 1 on your tax form will result in a penalty payment , and any way you have not stated your units .
otherwise you are playing with meaningless symbols .to paraphrase your "proofs"
x=0.999999...
10x=9.999999...
10x-x = 9.999999... - 0.999999...
9x = 9Therefore x=1thereforethus x-1.0000000000 =0.0000000000000000000000000................where x=1
or0.999999999..... - 1 = 0.11111111111111111111111111111111 ........where x=0.99999999999999999...............mind you for you corporate accounts it might help with your negative proof situation ...
which is it ?????????Edited by ikabod, : opss pressed submit by mistake

ACtually, riVeRraT has a point. You have not demonstrated that the entities you are attempting to subtract exist. And in constructivism, they don't.Not that I'm even remotely a constructivist, but it should be recognised.

rR has a point in that he stated it can't be done. I have the same strength of point in that I said it can. That's as advanced as the debate is right now

Good point.Mathematics deals with far more than the usual numbers (an representations of numbers) that we meet in everyday experience. It is more the logical manipulation of symbols, some of which relate to the numbers of our experience. Some symbols appear to have no correspondance to our experience, but certain manipulations bring them back to more everyday objects.Take for example i, the sqrt of -1. It has no real (everday) meaning as you would understand it, except that i^4 = 1, which ties it down to things we can understand. Similarly with the infinite strings of digits that make up recurring decimals and irrational numbers.

That would imply that 0.999999999... + 0.11111111111.... is 1. Actually that bit of maths gets you 1.1111111111111.....Doing it in fractions:9x¹⁄₉ - 1 = 0Your maths '0.999999999..... - 1 = 0.11111111111111111111111111111111 ........' would look like this:9x¹⁄₉ - 1 = ¹⁄₉That leads to the unusual concept of ⁹⁄₉ + ¹⁄₉ = ⁹⁄₉

Drugs.Oh wait that's not it - It's because I saw this:Credit Scores, Reports & History | Equifax UK

If 0.99999... doesn't exist, then isn't the statement 0.9999....=1 vacuously true? Maybe I'm just thinking about it too much?

Hmmm, I'm not sure of your logic there. You can simply define the symbol .999999... to be 1, but that sort of defeats the object. 1 divided by 3 yields .3333333..., and as a physical (constructable) process never yields the precise 1/3. We would like to imagine the process continuing to infinity to make the answer precise and then treat these infinite strings as simple continuations of the finite decimals, obeying the same operations. One must then ensure that these infinite strings remain consistent under these operations.Fortunately, they are But the constructivist will never believe you becasue you can never produce one! One can never think about maths too much