Divide 1 by 3.  1/3 = .3333333333333333333333333333333333333333333333333333333333333333333...

Divide 2 by 3.  2/3= .6666666666666666666666666666666666666666666666666...

Now add 1/3 + 2/3.  That equals one whole, right?

 .3333333333333333333333333... +.66666666666666666666666666...= .999999999999999999999999999999...

which means...

1/3 +2/3= .99999999999999999999999999...

hence

1=.99999999999999999999999999999...

Simplest way I can explain it.

Since I'm an idiot explain to me, all this because you can divide a number into ever increasingly parts until it disappears up your arse never to be seen again ,and nobody likes infinity except that well known Mathematician Buzz Lightyear who showed us the way and went beyond infinity ,we decided to say fuck it lets call it a day and make it for all intents and purposes equal 1. , nothing wrong with that except what happens when you start to multiply 0.999 by say a million compared to 1 x the same number do you ignore the difference.

It's kinda hard to grasp. On one hand 0.33333 = 1/3 so 0.99999 should be 1, but on the other hand, it stars with 0 so it's technically an infinitesimal smaller :P

 I must have posted this part by accident because my full statement is underneath , thank you anyway appreciated.

Mathematics isn't a property. Does it make sense to say that a cup has property math? No, this is utter nonsense it's totally incoherent to say so. 

That's problem 1. Problem 2 is Platonism in general. To say that the conception of something lives externally is to commit the absurd self-refuting idea that that which is conceptual is the same as that which is actual.

So what you are saying is that the universe doesn't have mathematical properties? What is pi then? Is there not a mathematical relation between the diameter and the circumference of a circle?

I didn't even claim that there was mathematical properties to everything. However I do think there are inherent mathematical properties to how the universe works, and it is these properties we exploit on physics.

I'm sorry if you can't understand my comment, however that isn't my problem.

Your continued bald assertion that the Universe has mathematical properties is actually referred to as special pleading. In the future please do better when lodging responses. I see nothing here to respond to as piling on more assumptions only hinders progress of your rather inept contention.

By the way if you think a circle is something which has a referent you are sorely confused about mathematical objects.

my answer to that is  yes a 1/3 and 2/3 = one whole but .333 recuring added to .666 recuring doesn't simply because it ignores the recuring part.

If d = infinitely small number
x = 0.999... = 1 - d
x = 1 - d
10x = 10 - d
10x = 9 + 1 - d
10x = 9 + x
9x = 9
x = 1

This makes sense right? An infinitely small number multiplied by 10 is still an infinitely small number.

Not really I think. If 10d = d then dividing by d gives you 10 = 1. My guess is that the problem takes advantage of this fact.

But... 1/3 is equal to .333... and 2/3 equals .666... they're interchangeable. They're different ways to denote the same amount.  

Replace the fractions in the equation with their decimal equivelants.

.333333333 (1/3)+ .666666666 (2/3)= .99999999 (1)

The thing is that you're not really dealing with infinity.  .33333333... is a specific finite amount that is equal to exactly one third. The numbers may go on and on in theory but the quantity they represent is specific amount.  It just so happens that in a base ten system, with the way division works, certain ratios (fractions) can only be represented in decimal form using repeating decimals.  The number itself is not infinite, the language we use to describe it is. It's just a quirk of our number system.  

For example, if we used a different number system, base 3 for example, we wouldn't have the problem of repeating numbers.  .333333333333... (1/3)in base 3 would simply be .1.  And in base 3, .66666666666... (2/3) would simply be .2.  If you added those two numbers, it would come out to a nice even 1.  And if 1/3+2/3=1 in a base 3 system, it has to also equal that in a base 10 system.  

(in base 3 .1+.2=.3  But, in a base 3, the only digits are one and two.  When you get to 3, you carry it over a place, like when you get to ten in base 10.  So, .3 would become 1.  1 in base 3 is the same as 1 in base 10)

Dunno if that helps, but the point is there is nothing inherently repeating about numbers like 1/3 or 2/3.  They don't *have* to be repeating numbers, it just so happens that due to the limitations of working with the particular number system we use, we can't describe these numbers in decimals without them repeating.