Is 1 = 0.9999......

Page 3 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

Kyteland

Diamond Member
Dec 30, 2002
5,747
1
81
Originally posted by: Skoorb
if .99999999999 = 1 then it would be 1 not, .99999999

Yes, but aren't they different representations for the same thing? By your logic i=sqrt(-1) are not the same thing because if i=sqrt(-1) then it would be sqrt(-1) not i.

And I know that this is a silly argument, but it kinda illustrates the point that your perception of them being equal or not before hand influences if you think they are equal when you are asked.

If that made any sense.....
 

TuxDave

Lifer
Oct 8, 2002
10,571
3
71
Originally posted by: Skoorb
if .99999999999 = 1 then it would be 1 not, .99999999

Just like 4/2 can't equal 2 because then it would be written as 2, not 4/2
 

josphII

Banned
Nov 24, 2001
1,490
0
0
1 does equal 0.999..., it is mathematical FACT

heres the proof:

Proof: 0.9999... = Sum 9/10^n
(n=1 -> Infinity)

= lim sum 9/10^n
(m -> Infinity) (n=1 -> m)

= lim .9(1-10^-(m+1))/(1-1/10)
(m -> Infinity)

= lim .9(1-10^-(m+1))/(9/10)
(m -> Infinity)

= .9/(9/10)

= 1
 

Mday

Lifer
Oct 14, 1999
18,647
1
81
this question has been asked before. check highly techical or something.

the sequence of numbers .9 .99 .999 .99.... etc does converge to 1.

while it's not proper to say that .9999... = 1, it's a matter of rhetoric.

yes, i've taken real analysis.
 

silverpig

Lifer
Jul 29, 2001
27,703
12
81
What some ignorant people may think:

0.999... = the "last" number in 0.9, 0.99, 0.999, 0.9999... etc

WRONG

0.999... is not a progression. You don't add nines, or "take" nines, or approach anything. How can a number approach another number? It doesn't. Sums approach numbers, numbers are just numbers.

0.999... is 1.


For all of you who say it isn't:

1. In order to prove that two numbers a and b are different, you must be able to explicitly define another number, c, that is larger than a and smaller than b. For example:

Let a = 4
Let b = 5
4 < 5 because if we let c = 4.5 we have a < c < b ===> 4 < 4.5 < 5

Therefore 4 < 5.

Now try that with 0.999... and 1.

There is no way to write that difference because it does not exist. But, a common way to write differences is by doing it this way:

0.9r = w + x
1 = y + z

w,x,y, and z must be defined numbers though.

w < a < y
x < b < z
w + x < a + b < y + z

Therefore 0.9r < 1.

All you have to do now, is come up with numbers for w,x,y,z,a, and b.
 

Dark4ng3l

Diamond Member
Sep 17, 2000
5,061
1
0
This is easey, 9.9999... is not exact(like pi,it's an estimated value) it essentially represents 3/3 witch is 1
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: silverpig
What some ignorant people may think:

0.999... = the "last" number in 0.9, 0.99, 0.999, 0.9999... etc

WRONG

0.999... is not a progression. You don't add nines, or "take" nines, or approach anything. How can a number approach another number? It doesn't. Sums approach numbers, numbers are just numbers.

0.999... is 1.


For all of you who say it isn't:

1. In order to prove that two numbers a and b are different, you must be able to explicitly define another number, c, that is larger than a and smaller than b. For example:

Let a = 4
Let b = 5
4 < 5 because if we let c = 4.5 we have a < c < b ===> 4 < 4.5 < 5

Therefore 4 < 5.

Now try that with 0.999... and 1.

There is no way to write that difference because it does not exist. But, a common way to write differences is by doing it this way:

0.9r = w + x
1 = y + z

w,x,y, and z must be defined numbers though.

w < a < y
x < b < z
w + x < a + b < y + z

Therefore 0.9r < 1.

All you have to do now, is come up with numbers for w,x,y,z,a, and b.

i like this answer but it still doesn't prove that 0.9999.... is equal to 1. Because if two numbers are different, then you can find a number that is between them. But with this particular case, the difference will be 1-0.99999.....
 

Haircut

Platinum Member
Apr 23, 2000
2,248
0
0
Originally posted by: Dark4ng3l
This is easey, 9.9999... is not exact(like pi,it's an estimated value) it essentially represents 3/3 witch is 1
So, why exactly is 9.9999... or indeed pi not exact?


 

McPhreak

Diamond Member
Jul 28, 2000
3,808
1
0
Originally posted by: TuxDave
That proof looks good to me. I believe 0.9999... = 1. For those who don't believe still, show me 1-0.999... doesn't equal 0.

And if you say it equals 0.000000.....001... there's an infinite number of zeros, so that '1' never really exists, so technically 1-0.999... = 0

Does that mean 0.99999.....98 = 0.999999999.....99?
 

Skyclad1uhm1

Lifer
Aug 10, 2001
11,383
87
91
Let's be nice annoying as usual, and confuse people

10*(1-0.9)=1
1 decimal, one zero.

100*(1-0.99)=1
2 decimals, 2 zeroes

1000*(1-0.999)=1
3 decimals, 3 zeroes.

1000...*(1-0.999...)=1?
infinite decimals and the same infinite number of zeroes?




(Edit: According to 0.999...=1 that would give 0 of course)
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Skyclad1uhm1
Let's be nice annoying as usual, and confuse people

10*(1-0.9)=1
1 decimal, one zero.

100*(1-0.99)=1
2 decimals, 2 zeroes

1000*(1-0.999)=1
3 decimals, 3 zeroes.

1000...*(1-0.999...)=1?
infinite decimals and the same infinite number of zeroes?




(Edit: According to 0.999...=1 that would give 0 of course)

heheh confusing everyone was my whole point. I bet even the people who thought they knew for sure, have taken a second, more deeper look into the problem.
 

josphII

Banned
Nov 24, 2001
1,490
0
0
Originally posted by: bleeb
Originally posted by: silverpig
What some ignorant people may think:

0.999... = the "last" number in 0.9, 0.99, 0.999, 0.9999... etc

WRONG

0.999... is not a progression. You don't add nines, or "take" nines, or approach anything. How can a number approach another number? It doesn't. Sums approach numbers, numbers are just numbers.

0.999... is 1.


For all of you who say it isn't:

1. In order to prove that two numbers a and b are different, you must be able to explicitly define another number, c, that is larger than a and smaller than b. For example:

Let a = 4
Let b = 5
4 < 5 because if we let c = 4.5 we have a < c < b ===> 4 < 4.5 < 5

Therefore 4 < 5.

Now try that with 0.999... and 1.

There is no way to write that difference because it does not exist. But, a common way to write differences is by doing it this way:

0.9r = w + x
1 = y + z

w,x,y, and z must be defined numbers though.

w < a < y
x < b < z
w + x < a + b < y + z

Therefore 0.9r < 1.

All you have to do now, is come up with numbers for w,x,y,z,a, and b.

i like this answer but it still doesn't prove that 0.9999.... is equal to 1. Because if two numbers are different, then you can find a number that is between them. But with this particular case, the difference will be 1-0.99999.....

firstly i cant believe there are 42 idiots that think 1 is not equal to 0.9999..... but anyways

the difference between 1 and 0.999.... is 0.0000..... !!
 

josphII

Banned
Nov 24, 2001
1,490
0
0
Originally posted by: Haircut
Originally posted by: Dark4ng3l
This is easey, 9.9999... is not exact(like pi,it's an estimated value) it essentially represents 3/3 witch is 1
So, why exactly is 9.9999... or indeed pi not exact?

they are not exact because pi and 0.999... have an infinite number of digits
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: josphII
Originally posted by: bleeb
Originally posted by: silverpig
What some ignorant people may think:

0.999... = the "last" number in 0.9, 0.99, 0.999, 0.9999... etc

WRONG

0.999... is not a progression. You don't add nines, or "take" nines, or approach anything. How can a number approach another number? It doesn't. Sums approach numbers, numbers are just numbers.

0.999... is 1.


For all of you who say it isn't:

1. In order to prove that two numbers a and b are different, you must be able to explicitly define another number, c, that is larger than a and smaller than b. For example:

Let a = 4
Let b = 5
4 < 5 because if we let c = 4.5 we have a < c < b ===> 4 < 4.5 < 5

Therefore 4 < 5.

Now try that with 0.999... and 1.

There is no way to write that difference because it does not exist. But, a common way to write differences is by doing it this way:

0.9r = w + x
1 = y + z

w,x,y, and z must be defined numbers though.

w < a < y
x < b < z
w + x < a + b < y + z

Therefore 0.9r < 1.

All you have to do now, is come up with numbers for w,x,y,z,a, and b.

i like this answer but it still doesn't prove that 0.9999.... is equal to 1. Because if two numbers are different, then you can find a number that is between them. But with this particular case, the difference will be 1-0.99999.....

firstly i cant believe there are 42 idiots that think 1 is not equal to 0.9999..... but anyways

the difference between 1 and 0.999.... is 0.0000..... !!



PROVE IT =)
 

aux

Senior member
Mar 16, 2002
533
0
0
Someone may have posted this but I'm too tired to read the whole thread.
Here it goes: 0.9999... = 9*0.1111... = 9 * (10^(-1) + 10^(-2) + 10^(-3) + ....)
now, 10^(-1), 10^(-2), 10^(-3), ... is a geometric progression that sums up to (10^(-1) )/ ( 1- 10^(-1)), which is exactly 1/9
therefore 0.9999... = 9* (10^(-1) + 10^(-2) + 10^(-3) + ....) = 9 * 1/9 = 1
 

911paramedic

Diamond Member
Jan 7, 2002
9,448
1
76
This is nuts.

I see how you could do the 10x-x=10 (x being 0.99999) so reduced it is x=1, but that just sucks my butt.

Try to prove it without manipulating the number at all. Does 1=0.99999... NO! Does it even look the same, no? Is it the same? Close, but no cigar.

 

Czar

Lifer
Oct 9, 1999
28,510
0
0
Originally posted by: josphII
Originally posted by: bleeb
Originally posted by: silverpig
What some ignorant people may think:

0.999... = the "last" number in 0.9, 0.99, 0.999, 0.9999... etc

WRONG

0.999... is not a progression. You don't add nines, or "take" nines, or approach anything. How can a number approach another number? It doesn't. Sums approach numbers, numbers are just numbers.

0.999... is 1.


For all of you who say it isn't:

1. In order to prove that two numbers a and b are different, you must be able to explicitly define another number, c, that is larger than a and smaller than b. For example:

Let a = 4
Let b = 5
4 < 5 because if we let c = 4.5 we have a < c < b ===> 4 < 4.5 < 5

Therefore 4 < 5.

Now try that with 0.999... and 1.

There is no way to write that difference because it does not exist. But, a common way to write differences is by doing it this way:

0.9r = w + x
1 = y + z

w,x,y, and z must be defined numbers though.

w < a < y
x < b < z
w + x < a + b < y + z

Therefore 0.9r < 1.

All you have to do now, is come up with numbers for w,x,y,z,a, and b.

i like this answer but it still doesn't prove that 0.9999.... is equal to 1. Because if two numbers are different, then you can find a number that is between them. But with this particular case, the difference will be 1-0.99999.....

firstly i cant believe there are 42 idiots that think 1 is not equal to 0.9999..... but anyways

the difference between 1 and 0.999.... is 0.0000..... !!
its actually 0.0000...1
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Here is a prove that is somewhat feasible:

Given:

Two numbers are not equal if the difference doesn't equal zero...

1 - 0.9 = 0.1

1 - 0.99 = 0.01

1 - 0.999 = 0.001

1 - 0.9999 = 0.0001

1 - 0.99999 = 0.00001

so on and so forth. You can clearly see there will always be a difference. Now the main point that everyone is saying that as this difference a super infinitely small number, it will converge to zero. Thus proving that the numbers are equal. But that only occurs when we reach the end of infinity. Which you can obviously tell will never happen. >=)
 

bigredguy

Platinum Member
Mar 18, 2001
2,457
0
0
If 1 does equal .99... then 1-.99... would equal 0, but it wouldn't 1-.99... = some miniscule decimal, something greater than 0.
.99...+x=1 if x has a value then they can't be the same.
 
sale-70-410-exam    | Exam-200-125-pdf    | we-sale-70-410-exam    | hot-sale-70-410-exam    | Latest-exam-700-603-Dumps    | Dumps-98-363-exams-date    | Certs-200-125-date    | Dumps-300-075-exams-date    | hot-sale-book-C8010-726-book    | Hot-Sale-200-310-Exam    | Exam-Description-200-310-dumps?    | hot-sale-book-200-125-book    | Latest-Updated-300-209-Exam    | Dumps-210-260-exams-date    | Download-200-125-Exam-PDF    | Exam-Description-300-101-dumps    | Certs-300-101-date    | Hot-Sale-300-075-Exam    | Latest-exam-200-125-Dumps    | Exam-Description-200-125-dumps    | Latest-Updated-300-075-Exam    | hot-sale-book-210-260-book    | Dumps-200-901-exams-date    | Certs-200-901-date    | Latest-exam-1Z0-062-Dumps    | Hot-Sale-1Z0-062-Exam    | Certs-CSSLP-date    | 100%-Pass-70-383-Exams    | Latest-JN0-360-real-exam-questions    | 100%-Pass-4A0-100-Real-Exam-Questions    | Dumps-300-135-exams-date    | Passed-200-105-Tech-Exams    | Latest-Updated-200-310-Exam    | Download-300-070-Exam-PDF    | Hot-Sale-JN0-360-Exam    | 100%-Pass-JN0-360-Exams    | 100%-Pass-JN0-360-Real-Exam-Questions    | Dumps-JN0-360-exams-date    | Exam-Description-1Z0-876-dumps    | Latest-exam-1Z0-876-Dumps    | Dumps-HPE0-Y53-exams-date    | 2017-Latest-HPE0-Y53-Exam    | 100%-Pass-HPE0-Y53-Real-Exam-Questions    | Pass-4A0-100-Exam    | Latest-4A0-100-Questions    | Dumps-98-365-exams-date    | 2017-Latest-98-365-Exam    | 100%-Pass-VCS-254-Exams    | 2017-Latest-VCS-273-Exam    | Dumps-200-355-exams-date    | 2017-Latest-300-320-Exam    | Pass-300-101-Exam    | 100%-Pass-300-115-Exams    |
http://www.portvapes.co.uk/    | http://www.portvapes.co.uk/    |