Ponder This

Welcome to the new home of Ponder This, the monthly IBM Research puzzles hosted by IBM Research - Israel. You are cordially invited to match wits with some of the best minds in IBM Research.

Some of us can't see a problem without wanting to take a crack at solving it. Does that sound like you?

Good. Forge ahead and ponder this month's problem. We post a new one every month and allow a month for you to submit solutions (we may even publish submitted answers, especially if they're correct).

We usually won't reply individually to submitted solutions, but every few days we'll update the list of people who answered correctly. After the beginning of the next month, we'll post the answer.

So give your mind a break from its routine. You never know what other problems you may solve in the process!

  • And now...

    Here's our February 2026 challenge!

    Ponder This

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    Ponder This

The last three challenges

Ponder This top 100 solvers

Last update: February 2026.

SolverChallenges solved
1Daniel Bitin208
2Dan Dima186
3David Greer163
4Radu-Alexandru Todor151
5Motty Porat145
6Clive Tong133
7Nyles Heise133
8Harald Bögeholz131
9Joseph DeVincentis125
10Daniel Chong Jyh Tar125
  • SolverChallenges solved
    1Daniel Bitin208
    2Dan Dima186
    3David Greer163
    4Radu-Alexandru Todor151
    5Motty Porat145
    6Clive Tong133
    7Nyles Heise133
    8Harald Bögeholz131
    9Joseph DeVincentis125
    10Daniel Chong Jyh Tar125
    11Lorenz Reichel124
    12Todd Will122
    13Kang Jin Cho122
    14Gary M. Gerken116
    15Andreas Stiller114
    16Amos Guler112
    17Reiner Martin112
    18Shouky Dan111
    19Chris Shannon110
    20Dieter Beckerle110
    21Tamir Ganor110
    22Alper Halbutogullari107
    23Liubing Yu105
    24Bert Dobbelaere105
    25Stéphane Higueret104
    26John Tromp104
    27David Friedman92
    28Vladimir Volevich92
    29Albert Stadler91
    30Li Li90
    31Shirish Chinchalkar88
    32Victor Chang87
    33Alex Fleischer87
    34Bertram Felgenhauer84
    35Armin Krauss84
    36Florian Fischer82
    37Latchezar Christov80
    38Marco Bellocchi78
    39John G. Fletcher77
    40James Dow Allen77
    41Franciraldo Cavalcante77
    42Mathias Schenker75
    43David F.H. Dunkley74
    44Chuck Carroll72
    45Don Dodson72
    46Michael Liepelt71
    47Graham Hemsley71
    48Hakan Summakoğlu69
    49Arthur Vause69
    50Oscar Volpatti69
    51Sanandan Swaminathan68
    52Peter Gerritson66
    53Dominik Reichl65
    54Hugo Pfoertner62
    55Uoti Urpala62
    56Balakrishnan V58
    57Fabio Michele Negroni58
    58Paul Revenant58
    59Michael Brand56
    60Luke Pebody56
    61Lazar Ilic54
    62Karl D’Souza52
    63Andrea Andenna52
    64John T. Robinson51
    65Tim Walters51
    66Jan Fricke50
    67Fabio Filatrella50
    68Yan-Wu He50
    69Arthur Breitman49
    70JJ Rabeyrin49
    71Guillaume Escamocher49
    72Adam Daire48
    73Sri Mallikarjun J48
    74Gale Greenlee47
    75Aviv Nisgav47
    76Erik Wünstel47
    77Thomas Egense46
    78Joaquim Neves Carrapa45
    79Oleg Vlasii45
    80Francis Golding44
    81Alan Murray44
    82Eden Saig44
    83Phil Muhm43
    84Christian Blatter43
    85Greg Janée42
    86Vladimir Sedach40
    87Kipp Johnson40
    88Tom Sirgedas40
    89Alex Wagner40
    90Wolfgang Kais38
    91Lorenzo Gianferrari Pini Pini38
    92Muralidhar Seshadri38
    93Erik Hostens38
    94Evert van Dijken38
    95William Heller37
    96Mark Pervovskiy37
    97Kai Guttmann37
    98Reda Kebbaj37
    99Andreas Eisele36
    100Steven Langerwerf36

Puzzlemaster of Ponder This

The current puzzlemaster of Ponder This is Gadi Aleksandrowicz. Previous puzzlemasters include Oded Margalit (2007-2020), James Shearer (2005-2009), and Don Coppersmith (1998-2005).

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

GA

Gadi Aleksandrowicz

IBM Quantum - Qiskit SDK
OM

Oded Margalit

Ponder This Puzzlemaster (2007-2020)
JS

James Shearer

Ponder This Puzzlemaster (2005-2009)
DC

Don Coppersmith

Ponder This Puzzlemaster (1998-2005)

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