IBM Research | Ponder This | March 2009 challenges

# Ponder This

## March 2009

<<February March April>>

Ponder This Challenge:

Because February's challenge was very difficult, we postponed the submission deadline by a month and we'll post the solution on April 1st. In the meantime, here is a more straightforward challenge:

There are several simultaneous solutions for the following two exercises (the second is a 90-degree rotation of the first):

```  a b c      g d a
+         +
d e f      h e b
=====      =====
g h i      i f c
```

One of them is

```5 8|3
|
1 4|6
===+=
7 2|9
```

Our challenge is to find a similar exercise in hexadecimal.

One can prove that a 4x4 is insolvable, so we added a few zeros and ask you to fit all 15 nonzero hexadecimal digits in

```  abcde       mjfa
+ fghi0       nkgb
jk00l     + 00hc
=====       00id
mn00o       ====
ol0e
```

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 ponder@il.ibm.com.

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

Challenge: 02/27/2009 @ 03:30 PM EST
Solution: 04/01/2009 @ 09:00 AM EST
List Updated: 03/24/2009 @ 01:00 PM EST

Gary M. Gerken (02/28/2009 12:51 AM EDT)
Peter Mattsson (02/28/2009 01:42 PM EDT)
Ioan Marius Popdan (02/28/2009 08:26 PM EDT)
Sangxia Huang (03/01/2009 03:19 AM EDT)
Al Zimmermann (03/01/2009 05:53 AM EDT)
Are Hjørungnes (03/01/2009 07:20 AM EDT)
John G. Fletcher (03/01/2009 06:22 PM EDT)
Balakrishnan V (03/01/2009 06:38 PM EDT)
Oscar Portela (03/01/2009 07:15 PM EDT)
Nyles Heise (03/01/2009 09:10 PM EDT)
Bernardino Romera Paredes (03/01/2009 09:27 PM EDT)
John T. Robinson (03/01/2009 11:17 PM EDT)
Steven Langerwerf (03/01/2009 12:58 PM EDT)
Amos Guler (03/01/2009 03:48 PM EDT)
Andreas Eisele (03/02/2009 12:33 AM EDT)
Michael Brand (03/02/2009 04:47 AM EDT)
Fabio Filatrella (03/02/2009 05:41 AM EDT)
Vladimir Sedach (03/02/2009 08:15 AM EDT)
Albert Stadler (03/02/2009 08:56 AM EDT)
Chris Lomont (03/02/2009 01:27 PM EDT)
Arthur Breitman (03/02/2009 01:43 PM EDT)
Dan Dima (03/02/2009 03:43 PM EDT)
Adam Daire (03/02/2009 05:00 PM EDT)
Dan Wood (03/02/2009 08:45 PM EDT)
Thomas Buchholz (03/02/2009 08:50 PM EDT)
Mauro Bampo (03/03/2009 10:28 AM EDT)
Dmitry Litvinenko (03/03/2009 11:40 AM EDT)
Fred Schalekamp (03/03/2009 11:40 AM EDT)
Igor Malashkin (03/03/2009 03:42 PM EDT)
Ashutosh Mehra (03/03/2009 12:54 PM EDT)
Harold Gutch (03/03/2009 05:42 PM EDT)
Chris Shannon (03/03/2009 06:15 PM EDT)
Don Dodson (03/03/2009 06:27 PM EDT)
Clive Tong (03/04/2009 06:19 AM EDT)
Muralidhar Seshadri (03/04/2009 06:12 PM EDT)
Tom Sirgedas (03/04/2009 08:22 PM EDT)
Jesse Kolman (03/05/2009 01:20 AM EDT)
Steffen Wolf (03/05/2009 11:09 AM EDT)
Bobby Brennan (03/05/2009 12:36 PM EDT)
Kalyana Chakravarthy (03/06/2009 01:15 AM EDT)
Michael Liepelt (03/06/2009 12:43 PM EDT)
Yuho Chu (03/06/2009 11:39 PM EDT)
David Hentrich (03/07/2009 06:33 PM EDT)
Michael Wegener (03/08/2009 05:36 PM EDT)
Tim Nordenfur (03/08/2009 08:15 PM EDT)
Guy Tannenbaum (03/09/2009 03:49 AM EDT)
Muharrem Görkem (03/09/2009 06:45 PM EDT)
Greg Janee (03/10/2009 12:04 AM EDT)
Benjamin Bachmann (03/10/2009 11:27 AM EDT)
Travis Meyer (03/10/2009 08:58 PM EDT)
Bradley Wild (03/11/2009 11:26 AM EDT)
Alex Taylor (03/11/2009 01:25 PM EDT)
David Friedman (03/11/2009 03:02 PM EDT)
Neil Smeby (03/11/2009 07:25 PM EDT)
Daniel Chong Jyh Tar (03/12/2009 12:50 AM EDT)
Michael van Fondern (03/12/2009 03:43 AM EDT)
Jochen Klein (03/13/2009 07:41 AM EDT)
Mark Buisseret (03/14/2009 05:53 PM EDT)
Bojan Basic (03/14/2009 06:35 PM EDT)
Nagendra Gulur Dwarakanath (03/16/2009 10:34 AM EDT)
Kin Keung Ma (03/16/2009 10:25 PM EDT)
Boris Nikolaus (03/17/2009 07:17 PM EDT)
Gaurav Raizada and Sourabh Agrawal (03/18/2009 10:16 AM EDT
Nick Miller (03/20/2009 01:45 PM EDT
Raj Mohan (03/22/2009 01:45 AM EDT
Daniel Bitin (03/22/2009 10:42 AM EDT
Nagy Zoltan (03/22/2009 08:42 PM EDT
Samuel Schwager (03/23/2009 11:57 AM EDT)
Mihai Cioc (03/23/2009 07:30 PM EDT)
Adriana Clerici (03/26/2009 01:23 PM EDT)
Bob DiMarco (03/26/2009 02:57 PM EDT)
Pritpal Ahuja (03/27/2009 11:53 AM EDT)
Siva Dirisala (03/27/2009 09:45 PM EDT)
Francois Galilee (03/28/2009 09:05 AM EDT)
Wei Shi (03/29/2009 03:45 AM EDT)
Stéphane Higueret (03/30/2009 08:38 AM EDT)

Attention: If your name is posted here and you wish it removed please send email to the ponder@il.ibm.com.