Another interesting fraction

soroban

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Jan 28, 2005
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We have: 189  =  0.01123595  ...\displaystyle \text{We have: }\:\dfrac{1}{89} \;=\;0.01123595\,\,.\,.\,.


The decimal is formed like this:\displaystyle \text{The decimal is formed like this:}

. . 0.01\displaystyle 0.0{\color{blue}1}
. . 0.001\displaystyle 0.00{\color{blue}1}
. . 0.0002\displaystyle 0.000{\color{blue}2}
. . 0.00003\displaystyle 0.0000{\color{blue}3}
. . 0.000005\displaystyle 0.00000{\color{blue}5}
. . 0.0000008\displaystyle 0.000000{\color{blue}8}
. . 0.00000013\displaystyle 0.000000{\color{blue}{13}}
. . 0.000000021\displaystyle 0.0000000{\color{blue}{21}}
. . 0.0000000034\displaystyle 0.00000000{\color{blue}{34}}
. . . . . . \displaystyle \vdots


It seems that: 110n=1Fn10n  =  189\displaystyle \displaystyle\text{It seems that: }\:\frac{1}{10}\sum^{\infty}_{n=1} \frac{F_n}{10^n} \;=\;\frac{1}{89}

. . where Fn is the nth Fibonacci number.\displaystyle \text{where }F_n\text{ is the }n^{th}\text{ Fibonacci number.}


Care to prove it?\displaystyle \text{Care to prove it?}
 
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