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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? […]

Le Monde puzzle [#1044]

March 12, 2018

A dynamic programming Le Monde mathematical puzzle: Bob and Alice are playing a game where Alice fills a one-litre bottle from a water fountain, and empties it between four buckets. Bob then empties two of the four buckets. Alice then fills again her bottle and empties it again in the buckets. Alice wins if she […]

Le Monde puzzle [#1043]

March 5, 2018

An arithmetic Le Monde mathematical puzzle : A number is “noble” if all its digits are different and if it is equal to the average of all numbers created by permuting its digits. What are the noble numbers? There is no need for simulation when plain enumeration works. After failing to install the R packge […]