Credited with solving this puzzle: Ponder This Challenge: In the string CABACB, each letter appears exactly twice and the number of characters between the “A”s is one, between the “B”s is two, and between the “C”s is three. The same problem with the letters A-E cannot be solved, but adding a space (in the form […]

Credited with solving this puzzle: Ponder This Challenge: IBM recently announced a commercial Quantum computer. Such a computer can factor large numbers, using a Shor algorithm. The challenge this month is to factor at least one of the following three numbers: 27771495424394652906650011597233066116343506387184320546233728271726480989807112498372640545334956743914011373 98296593067163321549931012857525979998165090637663230976866143160359417516252340928637985390415053795128313 1412534667091752138605679066750993949837793629454397369052717798704788621599573184763086599428517731585079 Bonus ‘*’ if you factor all three. Hint: The challenge is […]

Credited with solving this puzzle (w/ extra credit!): Ponder This Challenge: This month’s challenge is from Yan-Wu He (thanks!) For a non-zero number (in list) (a1,a2,..,an), its square is (…, an,..,a2,a1), Let’s call the number N “squareversed” if its square ends with the reverse of N. For example, N=69714 is “squareversed”, since its square is […]

Credited with solving this puzzle (w/ extra credit!): Ponder This Challenge: This month’s challenge is about IBM’s InterConnect 2016 conference. Assign each letter a different digit such that the following mathematical equations would be correct (** denotes exponentiation): a**connect = c (mod inter) a**connect = a**toe (mod at) a**connect = a**toe (mod cm) n**i = […]

Credited with a solving this puzzle.  Tricky one, only a couple solutions in the world submitted: Ponder This Challenge: Last month, Gene Amdahl, an IBM fellow who was the chief architect of the legendary IBM 360 system, died at age 92. In memory of his work, this month’s challenge focuses on the IBM-360 character set […]

Credited with solving this puzzle.  I added an extra twist to this one to make the phrase have some meaning and I set out to submit a second one that was inappropriate to make the judge chuckle 🙂 Ponder This Challenge: To mark the announcement by IBM CEO Ginni Rometty about a new era of […]

Credited with solving this puzzle.  This was fun software to write! Ponder This Challenge: Find a way to fold a loop of string in three-dimensional space such that all three projections will be loop-free (i.e., you won’t be able to make a path from a point to itself without backtracking). Provide your answer as a […]

Credited with solving this puzzle: Ponder This Challenge: Four people stand in line with hats on their heads. On the back of each hat is a unique number (i.e., no two people have the same number) between 1 and 6. Each person can see only the numbers of the people in front of him. One […]

Credited with solving this puzzle: Ponder This Challenge: IBM’s QRadar system keeps track of events by measuring something every second. It has an anomaly detection system that alerts the user when the current measurement is more than three standard deviations away from the average of all previous measurements. An imaginary attacker is trying to deceive […]

Credited with solving this puzzle: Ponder This Challenge: Three people are playing the following betting game. Every five minutes, a turn takes place in which a random player rests and the other two bet against one another with all of their money. The player with the smaller amount of money always wins, doubling his money […]

Credited with a solution for this puzzle: Ponder This Challenge: There are 24 letters in the Greek alphabet, from alpha, beta, and gamma, through chi, psi, and omega. The names of the letters are of different lengths, from short two-letter names like mu or pi through the seven letters in omicron. We want to generate […]

Credited with solving this puzzle: Ponder This Challenge: Let b = (2^3^4^5) / (e^n), otherwise stated as “two to the power of (three to the power of (4 to the power of 5)) over e to the nth power”, where n is an integer such that 1 < b < e. Find b, with an […]

Credited with solving this puzzle: Ponder This Challenge: 32 pebbles are placed on the six edges of a tetrahedron, as shown in the following figure. Two players are playing a game. Each player, on her turn, can take as many pebbles as she chooses, but a minimum of one pebble must be taken each turn, […]

Credited with solving this puzzle (w/ extra credit!): Ponder This Challenge: Design 25 cubes so that each cube’s six faces display integer numbers in the range 0,1,…,31 such that: On each cube, all the numbers are different Any given two cubes share exactly one common number Please give your answer as 25 lines of six […]

Credited with solving this puzzle: Ponder This Challenge: This month’s challenge is from Michael Kleber, based on a problem invented by David Wilson. Every second, a gun shoots a bullet in the same direction at a random constant speed between 0 and 1. The speeds of the bullets are independent uniform random variables. Each bullet […]

Credited with solving this puzzle: Ponder This Challenge: Inspired by the viral 2048 game (http://en.wikipedia.org/wiki/2048_%28video_game%29) game, this month’s question is a simpler one-dimensional version of it. Assume that random independent numbers, either 2 or 4 with a 50% chance each, come in from the right side of a bar with N slots. The numbers are […]

Credited with solving this puzzle: Ponder This Challenge: N lamps are set in a circle, and for each integer M you have a tool that can toggle the state (on/off) of any set of M consecutive lamps. Find a possible N which satisfies the following statements: The sum of its digits is less than 10. […]

Credited with solving this puzzle: Ponder This Challenge: This month’s challenge is from Michael Brand (thanks!) and a related riddle can be found as the December challenge on his site (“Using your Head is Permitted”, http://www.brand.site.co.il/riddles). Every Christmas, the employees of MegaCorp play a gift-giving lottery game. On the first of December, each of the […]

Credited with solving this puzzle: Ponder This Challenge: A three-dimensional cube has eight vertices, twelve edges, and six faces. Let’s call them 0-D, 1-D, and 2-D faces, respectively. Denote f(d,k) as the number of k-dimensional faces of an d-dimensional hyper cube, so f(3,1)=12. Find three cubes (with different dimensions d1, d2, and d3) such that […]

Credited with solving this puzzle (w/ extra credit!): Ponder This Challenge: 36 people live in a 6×6 grid, and each one of them lives in a separate square of the grid. Each resident’s neighbors are those who live in the squares that have a common edge with that resident’s square. Each resident of the grid […]

Credited with solving this puzzle: Ponder This Challenge: Thanks to Adir Pridor for the following challenge: A gardener plants a tree on every integer lattice point, except the origin, inside a circle with a radius of 9801. The trees are cylindrical in shape and all grow together at the same rate. As the trees grow, […]

Credited with solving this puzzle: Ponder This Challenge: This month’s challenge is based on a wooden puzzle presented at the tenth Gathering for Gardner conference at Atlanta. There are six sets of jobs. Each set is performed on a different server and each set contains jobs that take 1,2,3,…,10 minutes to run. Obviously, all six […]

Credited with solving this puzzle, this was a fun one: Ponder This Challenge: This month’s challenge is based on a model suggested by Harry Buhrman, Serge Fehr, Christian Schaffner, and Florian Speelman, who described the garden-hose model in their paper “The Garden-Hose Game: A New Model of Computation, and Application to Position-Based Quantum Cryptography” ( […]

Credited with solving this puzzle: Ponder This Challenge: Arrange the numbers 1, 2, 3,…, 63 on the nodes of a balanced binary tree of height 6 such that each distance 1, 2, 3,…, 62 is realized on an edge; i.e., it is the difference of two vertices which are connected with an edge. Please supply […]