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Conferences The CTK Exchange High school Topic #197
Reading Topic #197
Nikhil
guest
Sep-06-02, 06:38 AM (EST)
 
"math"
 
   Is 0.99999.... a rational number?

Is it less than one or equal to one?

Please help.


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Simon
guest
Sep-06-02, 08:07 AM (EST)
 
1. "RE: math"
In response to message #0
 
   Any reccuring decimal is a rational number.

To convert to a fraction simply put the reccuring number over as many nines as it has digits e.g. 0.333333 = 3/9
and 0.248248248248... = 248/999

Therefore:
0.99999... = 9/9 = 1

For an interesting demonstration of this, try doing 4/9 by long division then multiplying by 9 by long multiplication. You'd think it would give 4, since (4/9)*4 = 4


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jman_red
Member since Jul-2-02
Sep-06-02, 10:20 PM (EST)
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2. "RE: math"
In response to message #1
 
   A small mistake in your math, Simon, (4/9)*4 = 16/9. I think you meant to imply that 4/9 * 9 = 4, which would prove your point.

Nikhil, a proof of .9999... = 1. It is on cuttheknot somewhere but i am not sure where.

x = .99999...
10x = 9.9999...
10x - x = 9.999... - .999...
9x = 9
x = 1

jman_red


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lei you
guest
Oct-15-02, 10:31 AM (EST)
 
3. "RE: math"
In response to message #0
 
   then what will be the value of (0.999999...)^2 ?

(0.9999999...) must differ from 1 in someways


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RicBrad
Member since Nov-16-01
Oct-16-02, 07:30 PM (EST)
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4. "RE: math"
In response to message #3
 
   >then what will be the value of (0.999999...)^2 ?

the same as 1^2, the same as "one"^2, the same as (4/4)^2, etc...

>(0.9999999...) must differ from 1 in someways

Why?

1 and 0.99999... are different names for the same number. The number given by these two decimal representations is exactly the same.

Always remember that things like this are definitions, given meaning only by people, not inherently meaningful.

Rich


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Whymme
guest
Nov-14-02, 08:00 PM (EST)
 
5. "RE: math"
In response to message #0
 
   Another proof: Divide 0,9999999...... by three. The result is 0,33333.... People generally know that this is the way in which 1/3 is written. So 0,9999..../3 is the same as 1/3.

And another. Subtract 0,999999 from 1. The result is an endless number of zeroes - hence, zero. Therefore, there is no difference between 0,9999999...... and 1.

The one mentioned above is the most elegant, though.

Whymme


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