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Le Monde puzzle [#1000…1025]

March 28, 2017

Le Monde mathematical puzzle launched a competition to celebrate its 1000th puzzle! A fairly long-term competition as it runs over the 25 coming puzzles (and hence weeks). Starting with puzzle #1001. Here is the 1000th puzzle, not part of the competition: Alice & Bob spend five (identical) vouchers in five different shops, each time buying […]

Le Monde puzzle [#1001]

March 27, 2017

After a long lag (due to my missing the free copies distributed at Paris-Dauphine!), here is a Sudoku-like Le Monde mathematical puzzle: A grid of size (n,n) holds integer values such that any entry larger than 1 is the sum of one term in the same column and one term in the same row. What […]

Le Monde puzzle [#990]

January 12, 2017

To celebrate the new year (assuming it is worth celebrating!), Le Monde mathematical puzzle came up with the following: Two sequences (x¹,x²,…) and (y¹,y²,…) are defined as follows: the current value of x is either the previous value or twice the previous value, while the current value of y is the sum of the values […]

Le Monde puzzle [#940]

November 11, 2016

A sudoku-like Le Monde mathematical puzzle: On a 3×3 grid, all integers from 1 to 9 are present. Considering all differences between adjacent entries, the value of the grid is the minimum difference. What is the maximum possible value? In a completely uninspired approach considering random permutations on {1,..,9}, the grid value can be computed […]

Le Monde puzzle [#977]

October 3, 2016

A mild arithmetic Le Monde mathematical puzzle: Find the optimal permutation of {1,2,..,15} towards minimising the maximum of sum of all three  consecutive numbers, including the sums of the 14th, 15th, and first numbers, as well as the 15th, 1st and 2nd numbers. If once again opted for a lazy solution, not even considering simulated […]