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Digits of irrational numbers
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Voice_Of_Gods
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#1
Digits of irrational numbers
my imagination

Are there irrational numbers (but non-transcendental) which don't have a certain digit in their decimal expansion (for example, sqrt(2) has all the digits, from 0 to 9, in its decimal expansion)?

PostPosted: Thu Jun 10, 2004 3:46 am  Back to top 
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Michael Lipnowski
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#2
another thought

What's more interesting to me is whether \sqrt2 has infinitely many of each digit in its base b representation, b \geq 3.

If anybody knows anything about this, could you please post or give me a reference?

PostPosted: Thu Jul 15, 2004 6:41 pm  Back to top 
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Magnara
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#3
On a related note, I was wondering if it is possible to, given a sequence of digits of finite length, find that sequence somewhere in the decimal expansion of irrationals and transcendentals. If the answer to your question is yes, then the answer to mine is clearly not true for all irrationals and transcendentals, but I wonder if it is true for any and if so, which ones.

PostPosted: Fri Jul 16, 2004 4:27 pm  Back to top 
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rcv
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#4
Magnara wrote:
given a sequence of digits of finite length, find that sequence somewhere in the decimal expansion of irrationals and transcendentals.


I can't answer the previous two questions. We can think about magnara's question. Consider the decimal number a=1.01001000100001000001..., where each decimal digit "1" is preceded by an ever-increasing number of "0" digits. Clearly, this number is irrational. I will never find the sequence of digits "234" in the decimal expansion of this number.

On the other hand, if you are looking to find the sequence "234" in *some* irrational number, let b=234*a. Wherever you find the sequence "001" in a, you will find the sequence "234" in b.

PostPosted: Sat Jul 17, 2004 7:01 am  Back to top 
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belenos
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#5
rcv wrote:
Consider the decimal number a=1.01001000100001000001...



Just a question : is this number transcendantal or not (it's not a Liouville's number but it does not prove anything !).

PostPosted: Sat Jul 17, 2004 7:45 am  Back to top 
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Voice_Of_Gods
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#6
In my opinion, the number proposed by rcv is too articficialy constructed to be algebrical.

PostPosted: Sun Jul 18, 2004 4:21 am  Back to top 
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lolo
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#7
all of these are related to the still open Borel's problem :
"any algebraic irrational number should be normal in base b for any integer b>1 "
that means that any sequence of digits of lengh s should appears with the frequency 1/s in the base b expansion of such numbers.
Near nothing is known about that !

PostPosted: Sun Oct 31, 2004 2:11 am  Back to top 
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