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Subject: "wisdom of calling irrational numbers real"     Previous Topic | Next Topic
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Conferences The CTK Exchange Early math Topic #76
Reading Topic #76
rao
Member since Mar-23-07
Mar-23-07, 02:25 PM (EST)
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"wisdom of calling irrational numbers real"
 
   At the URL https://www.cut-the-knot.org/do_you_know/numbers.shtml#deficient
it'says,
Ian Stewart questions the wisdom of calling irrational numbers real: How can things be real if you can't even write them down fully?

Does this mean that he concedes that integers are real? If he does what is real about 1, 2, ...?

Rao


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alexbadmin
Charter Member
2340 posts
Mar-23-07, 04:53 PM (EST)
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1. "RE: wisdom of calling irrational numbers real"
In response to message #0
 
   >At the URL
>https://www.cut-the-knot.org/do_you_know/numbers.shtml#deficient
>it'says,
>Ian Stewart questions the wisdom of calling irrational
>numbers real: How can things be real if you can't even write
>them down fully?
>
>Does this mean that he concedes that integers are real?

I can't talk for Ian Stewart, but I'd think his sentiment is not uncommon. Most recently I came through the same notions but in a more rigorous form in N. Wildberger's Divine Proportions.

> If
> he does what is real about 1, 2, ...?

I do not know. On the other hand, John Conway and Richard Guy claim complex numbers to be real while real numbers are simple.


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kate
guest
Mar-11-09, 04:28 PM (EST)
 
2. "RE: wisdom of calling irrational numbers real"
In response to message #0
 
   I can write down irrational numbers fully. Example, use the square root sign and put a 2 under it. There, it's fully represented. Just because it's in base 10 doesn't mean it's not able to be represented fully in another base.


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alexbadmin
Charter Member
2340 posts
Mar-11-09, 04:35 PM (EST)
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3. "RE: wisdom of calling irrational numbers real"
In response to message #2
 
   You can name the number, yes. π is a number. Sure.

> Just because it's in base 10 doesn't
> mean it's not able to be represented
> fully in another base.

Rational number may have finite or infinite expansion depending on the base, e.g.

1/3 = (.1)3 and
1/3 = (.333...)10

If we consider only integer bases then irrational numbers have infinite expansions regardless of the base.


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