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List:       kde-edu
Subject:    Re: [kde-edu]: unified kde-edu style?
From:       Uwe Thiem <uwe () polytechnic ! edu ! na>
Date:       2002-08-08 11:58:41
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On Thursday 08 August 2002 12:36, Dominique Devriese wrote:
> Sebastian Stein <s5228@informatik.htw-dresden.de> writes:
> 
> > > - the possibility to practic conversions from fractions to decimal 
numbers
> > > and vica versa.  1/8 = 0.125
> > 
> > Ok. Do you know a good algorithm to convert 0.125 into 1/8?
> 
> err, you interpret it as 125/1000 and then you simplify ?
> 
> there's also an algorithm to convert decimal numbers of infinite
> length, but with a repeating part ( which means the decimal
> representations of all rational numbers ) into fractions...  I think
> the idea was to divide the repeating part by a number which you write
> down as x 9's where x is the length of the repeating part ( that's the
> best i can explain it in english :). E.g. 0,111... would become 1/9
> .  0.1212... would become 12/99 etc.  This is the way they explained
> it to us in high school, i'm sure there's an easy way to write this
> down in code...

With a being your periodical decimal number and n being the length of the 
period, you multiply a by 10^n and then subtract a:

a = 0.1111111

10a = 1.1111111

9a = 1
a = 1 / 9




b = 0.213213213213
1000b = 213.213213213213
999b = 213
b = 213 / 999

Uwe
 
-- 
Nothing is fool-proof given a sufficiently skilled fool.

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