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Le Monde puzzle [#1051]

May 18, 2018

A combinatoric Le Monde mathematical puzzle of limited size: When the only allowed move is to switch two balls from adjacent boxes, what is the minimal number of moves to return all balls in the above picture to their respective boxes? Same question with six boxes and 12 balls. The question is rather interesting to […]

Le Monde puzzle [#1045]

May 13, 2018

An minor arithmetic Le Monde mathematical puzzle: Take a sequence of 16  integers with 4 digits each, separated by 2,  such that it contains a perfect square and its sum is a perfect cube. What are the possible squares and cubes? The question is dead easy to code in R for (x in as.integer(1e3:(1e4-16))){ if […]

Le Monde puzzle [#1049]

April 18, 2018

An algorithmic Le Monde mathematical puzzle with a direct Alice and Bob play a game by picking alternatively one of the remaining digits between 1 and 10 and putting it in either one of two available stacks, 1 or 2. Their respective gains are the products of the piles (1 for Alice and 2 for […]

Le Monde puzzle [#1048]

April 1, 2018

An arithmetic Le Monde mathematical puzzle: A magical integer m is such that the remainder of the division of any prime number p by m is either a prime number or 1. What is the unique magical integer between 25 and 100? And is there any less than 25? The question is dead easy to […]

Le Monde puzzle [#1045]

March 19, 2018

An arithmetic Le Monde mathematical puzzle of limited proportions (also found on Stack Exchange): If x,y,z are distinct positive integers such that x+y+z=19 and xyz=p, what is the value of p that has several ordered antecedents?  If the sum is now x+y+z=22, is there a value of p=xyz for which there are several ordered antecedents? […]