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These are no fractions, are they? (Posted on 2006-09-05) Difficulty: 3 of 5
You are probably quite certain that the following numbers are irrational. But can you prove it?

a = 0.149162536496481...

b = 0.2357111317192329...

c = 0.1248163264128256...

See The Solution Submitted by JLo    
Rating: 2.5000 (2 votes)

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Some Thoughts solution for b ? | Comment 5 of 16 |
Not quite sure, but if we say that this sequence exists of the different primes concatenated as decimals, the sequence could not be periodic, I guess. If this would indeed be the case, then the proposed number is irrational.

This seems to be the case for a (the perfect squares concatenated) and c (the powers of 2, where the last digit of a power is always even, but the others become odd at some point, and the number of digits of a power increases gradually -- this would make it impossible to make the sequence periodic).

  Posted by Robby Goetschalckx on 2006-09-06 05:39:22
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