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List:       debian-devel
Subject:    Re: Stupid Arithmetic Tricks
From:       Erich Schubert <erich () debian ! org>
Date:       2002-03-30 9:53:41
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> A little knowledge of series tells me to apply n*(n+1)/2 to sum an arithmetic
> progression of common difference 1, starting at 1.  This seems even quicker:
> 100*101/2 becomes 5*101*10 becomes 505*10 = 5050.

Yep, but you aren't teached these formulas when in primary school you
just learned adding and summation... the teacher was said to have
expected his pupils to need the whole lesson for doing this calculation.
And Gauss was born 1777, and he really surprised his teacher by then,
presenting the solution that fast ;)

BTW: I just checked: gauss added 1+100, 2+99 etc. and got directly to
the calculation 101*50 ;)

Greetings,
Erich


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