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Ponder This

October 2011

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Ponder This Challenge:

We call a real number R "interesting" if the product of every 8 consecutive decimal digits is 40,320.

Build a network from no more than twenty 1-ohm resistors such that their overall resistance, see (external link http://en.wikipedia.org/wiki/Series_and_parallel_circuits for details) R would be interesting.

Please submit your answer as pairs of letters, in which each pair represents the endpoints of a resistor, where the overall resistance is measured between "a" and "z".

For example, the following network is a cube, measured along the long diagonal: "ab bc cd da ef fz zh he ae bf cz dh".

We know that atto-ohm accuracy is meaningless, but this is a mathematical challenge, not an electrical engineering one.

Hint: This month's challenge can be solved on the back of an envelope.


We will post the names of those who submit a correct, original solution! If you don't want your name posted then please include such a statement in your submission!

We invite visitors to our website to submit an elegant solution. Send your submission to the webmaster.

If you have any problems you think we might enjoy, please send them in. All replies should be sent to: webmster@us.ibm.com

  

Challenge: 10/01/2011 @ 10:00 AM EST
Solution: 11/01/2011 @ 10:00 AM EST
List Updated: 10/01/2011 @ 10:00 AM EST

People who answered correctly:

Jan Fricke (09/30/2011 08:32 PM EDT)
János Kramár (10/01/2011 12:22 AM EDT)
Yuanmi Chen (10/01/2011 08:27 AM EDT)
Alan Murray (10/01/2011 11:44 AM EDT)
Dan Dima (10/01/2011 12:54 PM EDT)
Leif Jensen (10/01/2011 01:22 PM EDT)
Pei Wu (10/02/2011 11:17 AM EDT)
Lu Wang (10/02/2011 12:04 AM EDT)
Piet Orye (10/02/2011 06:00 AM EDT)
Peter Gerritson (10/02/2011 07:26 PM EDT)
Ariel Flat (10/02/2011 08:19 PM EDT)
Arthur Breitman (10/03/2011 12:36 PM EDT)
Harold Gutch & Stefan Zehl (10/03/2011 01:15 PM EDT)
William Mantzel (10/03/2011 02:00 PM EDT)
Andreas Razen (10/03/2011 03:08 PM EDT)
Radu-Alexandru Todor (10/03/2011 07:21 PM EDT)
Chuck Carroll (10/03/2011 08:05 PM EDT)
Avishalom Shalit (10/04/2011 11:33 AM EDT)
Chris Kuklewicz (10/04/2011 04:58 PM EDT)
Adam Daire (10/04/2011 07:04 PM EDT)
Victor Chang (10/04/2011 08:49 PM EDT)
Josh Small (10/06/2011 11:54 AM EDT)
Ken Bateman (10/06/2011 02:40 PM EDT)
Shilei Zang (10/06/2011 03:46 PM EDT)
Yasodhar Patnaik (10/07/2011 03:26 AM EDT)
Gary M. Gerken (10/08/2011 08:01 PM EDT)
Renato Fonseca (10/09/2011 03:19 PM EDT)
David Greer (10/10/2011 07:45 AM EDT)
John Tromp (10/10/2011 12:50 PM EDT)
Maohua Sheng (10/10/2011 12:52 PM EDT)
Daniel Bitin (10/11/2011 11:07 AM EDT)
Phil Muhm (10/11/2011 02:53 PM EDT)
Armin Krauss (10/11/2011 03:14 PM EDT)
Liubing Yu (10/11/2011 06:30 PM EDT)
Adrian Neacsu (10/12/2011 04:21 PM EDT)
Hamidreza Bidar (10/12/2011 06:15 PM EDT)
Clive Tong (10/13/2011 05:09 PM EDT)
Movin Jain (10/14/2011 01:26 PM EDT)
Joseph DeVincentis (10/14/2011 10:08 PM EDT)
Pritibhushan Sinha (10/15/2011 04:48 AM EDT)
Peter de Rivaz (10/15/2011 04:59 AM EDT)
Dejan Stakic (10/16/2011 06:46 AM EDT)
David Friedman (10/16/2011 11:05 AM EDT)
Manoj vedvistara (10/16/2011 01:23 PM EDT)
Harald Bögeholz (10/16/2011 03:17 PM EDT)
Jeff Steele (10/17/2011 03:06 PM EDT)
Kipp Johnson & Nick Vigo (10/18/2011 11:58 AM EDT)
Tom Sirgedas (10/18/2011 08:45 PM EDT)
Chris Shannon (10/19/2011 01:04 AM EDT)
Jan Braunisch (10/19/2011 02:51 AM EDT)
Dr. Beena George (10/19/2011 05:02 AM EDT)
Stéphane Higueret (10/20/2011 10:07 PM EDT)
Franza Cavalcante Jr (10/21/2011 03:20 PM EDT)
Haoyu Bai (10/25/2011 01:01 AM EDT)
Thomas Rohr (10/26/2011 05:19 AM EDT)
Mathias Schenker (10/27/2011 11:10 AM EDT)
Yuan Yuan (10/28/2011 11:42 PM EDT)
Frederik Kaster (10/31/2011 03:02 PM EDT)


Attention: If your name is posted here and you wish it removed please send email to the webmaster.