# .9 Repeating = 1 YES -or- NO

## Does .9 Repeating equal to 1?   116 members have voted

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SCSIhunterD    0

the entire point of this discussion isn't realy about whether .999.......=1 but about whether there is a need for infestemial accuaracy

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snippet1    0
Dazzla and anyone who believes that .9999 is the same as 1, needs to go back to school or should not have dropped out.

I showed your calculations were incorrect, and you laugh cause you think I'm wrong??? Please. Calculators don't lie.

Sadly, calculators tend to get confused, in which case, they lie.

And BTW, think about it - no matter how many calculations you do, 0.9999999999999 will NEVER equal 1. They are two seperate numbers. It's like if you take a step towards a wall. Then you take half a step. Then you halve the size of that step. You continue on, taking each step half the size of the step before and you will NEVER reach the wall. You will get very close, but you will never touch the wall.

Oh, and remember that theory - 'The most obvious answer is probably the correct one'

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SCSIhunterD    0
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

you add 0.000000000...1 a.k.a. the smallest possible number/ an infestemialy small number / s

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bangbang023    31
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

u cant add that when 0.999... goes on forever. there is no place to add such a number. your 0.0000....1 assumes that infinity has and end which it does not.

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ike    0
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

u cant add that when 0.999... goes on forever. there is no place to add such a number. your 0.0000....1 assumes that infinity has and end which it does not.

he never said it was possible to type it into your calculator.

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SCSIhunterD    0
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

u cant add that when 0.999... goes on forever. there is no place to add such a number. your 0.0000....1 assumes that infinity has and end which it does not.

no it doesn't assume that it terminates- it assumes that both numbers extend to the same number of decimal places, which happnes to be infenite for both numbers.

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snippet1    0
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

u cant add that when 0.999... goes on forever. there is no place to add such a number. your 0.0000....1 assumes that infinity has and end which it does not.

You have to use infinity in the equation.

0.9999999... + 1e-infinity

or

0.9999999... + (1^10 * infinity)

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John    7
0.9999...

if that isn't equal to 1, what can you add to it to make it equal?

someone may have already answered this... you can "add" an infinitely small number. basically the difference between a number and a limit going to that number... if you've taken pre-calculus, this should make sense.

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ike    0

hrmm....

what fraction gives us .9999repeating ?

i just rethought my example above and realized how pointless it is in relation to this. because 9x = 3, 3/9 is still 1/3 :blush: i'm friggin tired.

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ericnkatz    1
hrmm....

what fraction gives us .9999repeating ?

i just rethought my example above and realized how pointless it is in relation to this. because 9x = 3, 3/9 is still 1/3 :blush: i'm friggin tired.

9/9 s gives you .999 [repeating]

But 9/9 s gives you 1 as well

I havent taken calculus nor pre cal, and neither have the two friends of mine included in the first post,

So according to what we have learned so far there is nothing between .9 [Repeating ] and 1

You cant have an infinite number of placements and have a 1 at the end nulifying the point of infinity

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Daem0hn    0

0.99999... = x

1 = y

x doesnt equal y

1-x=1*10^-infinity

1-y=0

if x=y then

(1-x)=(1-y)

however small teh difference it does not = 0 therefore x doesnt = y

i also have a proof that 1=0 i just need to find it

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brianicoleman    0

:blink: .999999=.999999 and 1=1, and im going to stick with that

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ericnkatz    1

What is the so called calculus anti- Proof for, 1 = .9999 [repeating]

I can only assume if there is no proof against it that it must be true

I have asked 3 math teachers and gotten the same answer "YES" I have asked other teachers and students and I get the Answer "NO"

I must assume that I am correct when i am asking math teachers and the response im getting is yes and when i ask average ordinary people i get the response no

Meaning the must be something else at a higher level than algebra that prooves this right or wrong,

If you have an anti proof that i agree with post it and i will tell everyone i am wrong and that my math teachers are wrong and the rest of you will be free to vote "NO" all you like,

But i havent heard such a proof yet,

My Geometry teacher and one of the high school pre cal/ trig teachers has agreed with me,

So please if you dont have an anti proof that works dont just be like "its impossible" and vote "NO" inconclusively.

Because you arent voting with all the facts... just the faint knowledge in your head saying its infinitely gettting closer to 1 cause the fact is when it gets to the point that there is nothing in between the numbers you must see that they in fact are equivelant.

Edited by Proxy
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John    7

.9999 repeating forever IS NOT 1, it's .9999 repeating forever. it is approaching 1, it keeps adding another digit at the end, TRYING to get to one, but it never does. it's NOT 1. get a calculus book and learn limits.

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CatnipOligarchy    1

i dont feel like reading all the logic.. im gonna go with 1=1, .9999=.9999 .. not the same thing

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ike    0

was looking in my math book today (by some mishap i'm in college algebra right now, but that's not the point)

found a section entitled "Writing a Repeating Decimal as a Fraction"

it basically says that you can use the following:

let's say you want to find 0.7777repeating as a fraction

(7/10)/(1-(1/10)) is their formula, which comes out to 7/9

at the end of that example it says "Express 0.999repeating as a fraction in lowest terms." i thought this was oh-so-convenient, heh

the answer in the back of the book is "1"

i'll take a pic of it later if you all want.

one thought that crossed my mind is that when you type in say, 7/9 in a calculator, you get 0.77777777777777777777777777777778 with the last digit rounded up. so in thinking about it, if you somehow got 0.9999repeating on a calculator, if you rounded up the last digit, the number would round up to 1, would it not?

another thing i thought of is the issue of .9999repeating + what = 1

if you have .8888repeating you can add .1111repeating to get .9999repeating ... but this is the same as 1/9 + 8/9 which would equal 1.

i think dazzla may have the right answer, but i question his method.

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ike    0

oh another thing, i punched in 1/<infinity> on my calculator today (TI-89) and it gave me the definite answer of 0. which i thought was interesting, because i thought that it'd be infinitely close to 0 but not 0. i expected it to give me 1/<infinity> back.

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ericnkatz    1

READ ---------------------------------- HERE IS THE FACTS

Dont go further in this topic without reading this post.

Dazzla in his first post in this topic was correct

x = 0.9999...

10x = 9.9999...

10x - x = 9x

9.9999... - 0.9999... = 9

9 = 9x

1 = x = 0.9999...

Here from an official math forum

http://mathforum.org/library/drmath/view/55746.html

Click and read, and be amazed. as they are EQUAL

Edited by Proxy
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Coolme    0

So basically, unless you specify an ending E.G. 0.999 it's equal to 1, right?

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Malechai    120

Dazzla's got skills

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Samoa    0
Dazzla's got skills

Dazzla may have skills ....however

10x-x=9x which everyone supporting the idea that .9999.... is equal to 1 seems to not understand that once you multiply a infinite number by a non-infinite number the result is a finite number (non-infinite).

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Malechai    120

no offense seriously, but what you just said may as well been blah blah blah because after reading the page at the link Proxy provided (http://mathforum.org/library/drmath/view/55746.html), well... frankly.. if i had to choose who knows more about this, i'd choose dr. math. sorry!

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ike    0

samoa, calc.exe would disagree with you.

type in 1/3=

you see .3333...

type *10=

you see 3.3333...

type /10=

type *3=

this will give you 1.

which would indicate to me that it still remembered internally that it is repeating

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John    7

ike: calculators round. and samoa's right; when you multiply .999... by 10, the result is not infinite. it's 9.999...9

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ike    0

ermm? wouldn't my calc example be a show of NOT rounding, rather than rounding?

if it rounded it, wouldn't it come up with a result in the very end such as .999999999999 (NOT repeating, and thus, not rounded)

type 1/3 in. you get 0.33333333333333333333333333333333

press ctrl-c to copy, hit escape, ctrl-v, then multiply it by 3, you then get 0.999999999999999999999999999999

(it no longer knows that it's a repeating .3)