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Topic:
make 100 by using 1, 7, 7, 7, 7
Replies:
41
Last Post:
Nov 15, 2007 6:13 PM




Re: make 100 by using 1, 7, 7, 7, 7
Posted:
Nov 13, 2007 12:14 PM


magidin@math.berkeley.edu (Arturo Magidin) wrote: > In article <20071113114106.785$O1@newsreader.com>, > David W. Cantrell <DWCantrell@sigmaxi.net> wrote: > >amzoti <amzoti@gmail.com> wrote: > >> On Nov 13, 7:28 am, "Benjamin A. Bartsch" > >> <benjamin.a.bart...@gmail.com> wrote: > >> > dangerousgam...@gmail.com schrieb: > >> > > >> > > So, using only +, , x, /, and parentheses, and ONLY these > >> > > numbers: > >> > > >> > > 1, 7, 7, 7, 7 > >> > > >> > > how can you make 100? Is there more than one solution? > >> > > >> > > (7+1/7)*7*(7/7+1) > >> > > >> > Benjamin > >> > >> That has five 7's and you are only allowed 4. > > > >Right. But I'm not sure that the "solution" 177  77 is legitimate > >either since it uses juxtaposition, which is not something which the OP > >mentioned that could be used. > > > >Here's a different solution which does not use juxtaposition: > > > >7 x 7 + 7 + 7 + 1 > > Using the usual precedence of operations, you have that this is equal > to (7x7) + 7 + 7 + 1, which comes out to 64.
It gives 64 in decimal; it gives 100 in octal. ;)
David
> I can't come up with any way to associate them to get 100, though: > > [7 x (7+7)] + 7 + 1 = 106 > [7 x (7+7+7)] + 1 = 148 > 7 x (7 + 7 + 7 + 1) = 154 > > So... how did you get 100?



