Math Recreations
Mathematical recreations: enigmas and fun puzzles
666: When the devil shows up in math | Tangente
From the biblical 666 to the Belphegor number, certain numbers send a shiver down the spine… and bring a smile to mathematicians' faces. Behind these "cursed" objects, the creativity and ingenuity of recreational mathematics run wild, ranging from number games to diabolical curiosities.
Three cheers for France! | Tangente
The international final of the Mathematical and Logic Games Championship was held on August 23 and 24. This year, it took place in Mahdia, Tunisia.
Divisibility in 19th-century textbooks | Tangente
Divisibility rules are numerous and are used by everyone who practises mental arithmetic. Blending arithmetic with common sense, they are a source of countless mathematical recreations, and have long been used in teaching.
Martin Gardner: Itinerary of a genius | Tangente
Although he is known for his recreational mathematics and his work as a popularizer, Martin Gardner strangely never pursued a course of study in the discipline. Here are the surprising stages of his unusual path.
Recreational problems from the Arab-Islamic world
Mathematical recreations feature prominently in the Arab-Islamic tradition, yet they do not appear to have been collected in dedicated anthologies. Some examples, very well known in Europe, pose a real challenge to historians seeking to trace how they circulated.
Conjectures finally settled! | Tangente
New developments in the famous "moving sofa problem" and advances in triangle dissection.
The joy of mathematical discovery: amateur mathematicians | Tangente
Christian Boyer, Vincent Thill, Jean Moreau de Saint-Martin and Philippe Fondanaiche—all passionate amateur mathematicians—agreed to answer our questions about how their interest in mathematics began and the activities they have developed in their favorite areas.
Squaring polygons
Archimedes' Stomachion, the world's oldest puzzle, can produce thousands of shapes from fourteen polygonal tiles. But what about the inverse problem? Under what conditions do two given polygons have a common polygonal dissection, and how can one be found?
Gilles and the mathematics culture and games fair | Tangente
Two passions guided Gilles throughout his life: puzzles and popularizing mathematics.
On the road – Mathematical brief | Tangente
Both unusual—since it does not usually rest on its "base"—and harmonious, as it is a quadrilateral with four equal sides, the rhombus appeals to graphic artists, advertisers and other designers: it appears in puzzles, games, road signs, logos…
Mathematical games: 2023 final | Tangente
After two years without an international final because of the pandemic, the 36th Championship held its final outside France for the first time, in Lausanne, Switzerland, while the final round of the 37th Championship will take place on August 25 and 26, 2023, at Wroclaw University of Science and Technology in Poland
A theorem puzzle in pictures: Monday's challenge | Tangente
Since 2015, the Image des maths website (https://images.math.cnrs.fr) has featured a "picture-theorem puzzle" every Monday, taken from Geometry in Figures, a book published in 2011 by the young Russian mathematician Arseniy Akopyan (CreateSpace Independent Publishing Platform) and available in French as Figures sans paroles (Independently Published, 2019).
The Mathematics of Tchoukaillon
Mancala is the generic name for traditional sowing games in Africa and Asia. One of the solitaire variants of these games gave rise to a mathematical recreation with unexpected properties and consequences.
A new president for the CIJM | Tangente
At the end of January, Brigitte Bourgasser Wenner succeeded Marie José Pestel as head of the International Committee for Mathematical Games (CIJM).
The point farthest from France's borders
Where is the "true" center of France? The question sometimes crops up among fans of recreational mathematics and divides enthusiasts of geographical curiosities. Depending on the criterion used to define this center, it may lie in the Cher, the Indre or… the Finistère!
The Rubik's Cube group: The mathematics of the magic cube | Tangente
The Rubik's Cube is a hugely popular puzzle among children and adults alike. This object, too, has its own group: all the isometries that leave it invariant.
Let’s bite into maths: 2021 Fair | Tangente
Get a first glimpse of the programme for the 22nd Culture and Mathematical Games Fair. Held online, it will be accessible to everyone, from anywhere.
The Bernard-Novelli prize: Mathematical news brief | Tangente
Another Tangente Trophy will be awarded this year: the Bernard-Novelli Prize. Run for several years with CASIO’s support, it recognizes a middle- or high-school student—working alone or in a group—who has written a computer program based on a mathematical game.
In logic and combinatorics
In mathematical and logical puzzles, often inspired by observations of everyday life, polynomials can crop up in surprising ways. Geometry, binary logic and algorithms, peg games, combinatorics… no field is immune!
Philippe Charbonneau: mathematical sculptor | Tangente
The artist Philippe Charbonneau (1936–2019), well known to Tangente readers, died a few days after the Mathematical Culture and Games Fair, which he had attended.