Re: Square roots - decimal expansions --

> JEMebius <jemebius@xxxxxxxxx> writes in article
> <42DD4FB8.6060802@xxxxxxxxx> dated Tue, 19 Jul 2005
> 20:08:40 +0100:
> >BTW, for palindromic decimal expansions just take a
> palindromic string
> >of digits, and interpret is as a decimal expansion
> or as the period of a
> >decimal expansion.
> >It equals some rational number p/q, but there is no
> general rule to
> >predict from given p and q if p/q has a palindromic
> period.
>
> Hmmmm, I think I can write one.
>
> First count the powers of 2 and of 5 in q. Whichever
> of these is greater,
> call m-1 (meaning m is one more than that number).
> m-1 is the number of
> non-repeating digits after the decimal.
>
> Find the first n such that q|(10^n-10^m)
>
> Let p' = p * (10^n-10^m)/q mod (10^(n-m)-1)
>
> If p' is a (n-m) digit palindrome, p/q has a
> palindromic period.
>
> --Keith Lewis klewis {at} mitre.org
> The above may not (yet) represent the opinions of my
> employer.

I'm too weak, an example please!
.

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