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

 Messages: [ Previous | Next ]
 David W. Cantrell Posts: 827 Registered: 7/2/06
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?

Date Subject Author
11/12/07 dangerousgame95@gmail.com
11/12/07 Thomas Nordhaus
11/12/07 amzoti
11/12/07 quasi
11/12/07 dangerousgame95@gmail.com
11/13/07 magidin@math.berkeley.edu
11/12/07 Thomas Nordhaus
11/12/07 quasi
11/12/07 Joshua Cranmer
11/12/07 Raymond Manzoni
11/13/07 William Elliot
11/13/07 amzoti
11/12/07 David R Tribble
11/12/07 Nat Silver
11/12/07 Raymond Manzoni
11/12/07 Raymond Manzoni
11/13/07 benjamin.a.bartsch@gmail.com
11/13/07 amzoti
11/13/07 David W. Cantrell
11/13/07 magidin@math.berkeley.edu
11/13/07 David W. Cantrell
11/13/07 magidin@math.berkeley.edu
11/13/07 briggs@encompasserve.org
11/13/07 Robert Israel
11/13/07 Dave Seaman
11/13/07 benjamin.a.bartsch@gmail.com
11/13/07 amzoti
11/13/07 David W. Cantrell
11/13/07 Jan Kristian Haugland
11/13/07 Robert Israel
11/13/07 Kira Yamato
11/13/07 Kira Yamato
11/13/07 Robert Israel
11/13/07 amzoti
11/14/07 Thomas Nordhaus
11/15/07 Michael Press
11/14/07 Michael Press
11/15/07 Kira Yamato
11/15/07 Michael Press
11/15/07 Rick Decker
11/13/07 Raymond Manzoni