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From: gjerawlins@watdaisy.UUCP (Gregory J.E. Rawlins)
Newsgroups: net.math
Subject: Re: Ashby's solution to 1+11+...n 1's seems to be in error
Message-ID: <6971@watdaisy.UUCP>
Date: Sat, 16-Feb-85 22:48:52 EST
Article-I.D.: watdaisy.6971
Posted: Sat Feb 16 22:48:52 1985
Date-Received: Sun, 17-Feb-85 06:32:43 EST
References: <595@decwrl.UUCP>
Reply-To: gjerawlins@watdaisy.UUCP (Gregory J.E. Rawlins)
Organization: U of Waterloo, Ontario
Lines: 20
Summary: 


[  A lot of mail redirection stuff plus the original problem deleted]
[  Problem is to find sum of series 1+11+111+...+ n 1's]
[  Ashby's solution of the problem is....]
 
>>         (2)  Sn = 10*(10^n -1)/81  -  n/9                                  
>                                                                            
>===========================================================================
> 
>There's something wrong with this solution !  s4 = 1+11+111+1111 = 1234.
>Let's  check: s4 = 10*(10^4-1)/81 - 4/9 = 10*9999/81 - 4/9 = 1234 + 16/81 -
>4/9 DOES NOT EQUAL 1234 !!  [(4/9)^2 = 16/81 but so what]

......perhaps you might check that 10*9999/81 = 1234 + 4/9 (not 16/81)

-- 
Gregory Rawlins CS Dept.,U.Waterloo,Waterloo,Ont.N2L3G1 (519)884-3852
gjerawlins%watdaisy@waterloo.csnet                              CSNET
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