About this #904 arithmetics Le Monde mathematical puzzle: Find all plural integers, namely positive integers such that (a) none of their digits is zero and (b) removing their leftmost digit produces a dividing plural integer (with the convention that one digit integers are all plural). a slight modification in the R code allows for a […]

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## Le Monde puzzle [#904.5]

March 25, 2015## Le Monde puzzle [#904]

March 25, 2015An arithmetics Le Monde mathematical puzzle: Find all plural integers, namely positive integers such that (a) none of their digits is zero and (b) removing their leftmost digit produces a dividing plural integer (with the convention that one digit integers are all plural). An easy arithmetic puzzle, with no real need for an R code […]

## Le Monde puzzle [#899]

February 8, 2015An arithmetics Le Monde mathematical puzzle: For which n’s are the averages of the first n squared integers integers? Among those, which ones are perfect squares? An easy R code, for instance which produces 333 values which are made of all odd integers that are not multiple of 3. (I could have guessed the exclusion […]

## Le Monde puzzle [#887quater]

November 28, 2014And yet another resolution of this combinatorics Le Monde mathematical puzzle: that puzzle puzzled many more people than usual! This solution is by Marco F, using a travelling salesman representation and existing TSP software. N is a golden number if the sequence {1,2,…,N} can be reordered so that the sum of any consecutive pair is a […]