Mathematical Themes
Explore the major mathematical themes: geometry, algebra, analysis, arithmetic, logic, and many other fascinating fields.
The Middle Ages, between representations and reality
While the allegorical representation of mathematics is always done through female figures, medieval reality allowed only a very few women to engage in it: a handful of nuns and high-ranking women, such as a Florentine widow who took over her husband's abacus school in 1330.
Where are the women in the history of mathematics?
The history of mathematics has been written almost exclusively by men. Yet many women mathematicians have existed: not only the great names, but also many names erased by history. Grace Chisholm, for example, is a striking case of what is known as the Matilda effect.
1897: Felix Klein's manifesto
In 1897, Felix Klein signed a feminist manifesto that, sadly, remains useful reading today for anyone who sees mathematics as an inherently male discipline.
Sofia Kovalevskaya and many others
Although Tangente is bringing you a special issue devoted entirely to women mathematicians, this is not the first time we have invited you to learn more about them.
Women mathematicians: a long-ignored history
This article explores the place of women in mathematics across the centuries, from the ancient world to the present day, and sheds light on those who have for too long been forgotten.
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.
Mathematical properties of 2026 | Tangente
Let's not break with our start-of-year tradition and explore together a few charming quirks of the new vintage!
A tribute to Michèle Audin | Tangente
Michèle Audin, a mathematician at the University of Strasbourg who specialized in symplectic geometry (at the intersection of differential geometry and dynamical systems), died on November 14, 2025.
Blaise Pascal’s Pascaline | Tangente
This past November 19, a Pascaline dating from 1642, valued at between two and three million euros, was due to go under the hammer at Christie’s in Paris.
Vampire numbers and their fangs | Tangente
Yes, vampire numbers really do exist! And they have fangs!
Parasitic numbers and permutations | Tangente
How do you multiply 105,263,157,894,736,842 by 2? Simple: just move the final digit, 2, to the front of the number, giving 210,526,315,789,473,684. And there you have it!
Conway's power trains | Tangente
Power trains are iterated functions introduced by Conway.
Multiplicative persistence of numbers | Tangente
Adding or multiplying together the digits of an integer is an activity a curious child might feel like doing. But they probably have no idea that it is the source of problems still unsolved in 2025!
Prime numbers and changing digits | Tangente
Unlike some composite numbers, it is hard to tell whether a number is prime just by looking at it. So what happens to a prime number if we make a change to its digits — for example, by permuting them or removing some of them? Can it stay prime? Or, on the contrary, does it stop being prime?
Narcissistic numbers and their secrets | Tangente
In the 1960s, while teaching at the University of Rochester in New York State, Mike Armstrong became particularly interested in k-digit numbers equal to the sum of the kth powers of their digits.
Palindromic numbers: numerical symmetry | Tangente
These numbers, which can be read equally well from left to right or from right to left, raise questions. At first glance they seem highly unusual, and therefore rare. Yet when an elementary arithmetic process is repeated on any whole number whatsoever, we almost always end up with just such a number. Bizarre, how bizarre!
It doesn't take much to be happy
We know that mathematics can be a source of joy, but have you heard of happy numbers? Simple to define, they hold plenty of surprises and show just how much playing with integers remains an inexhaustible source of research at every level.
Mirzakhani's mathematical vision | Tangente
In 2020, George Csicsery directed a documentary about Maryam Mirzakhani titled Secrets of the Surface: The Mathematical Vision of Maryam Mirzakhani. Through numerous firsthand accounts, it reveals the life, personality and work of the Iranian mathematician.
The magic wand theorem | Tangente
Maryam Mirzakhani is also known for having obtained, with Alex Eskin and Amir Mohammadi, the magic wand theorem, so named because it made it possible to solve at a stroke many previously inaccessible problems. To explain it, let's first delve into translation surfaces. The illumination problem is one of its many applications.
Mirzakhani's geodesics
Maryam Mirzakhani first became known for the work she carried out for her thesis, in which she counts closed geodesics on hyperbolic surfaces. To explain her results, we will take a short tour through the world of hyperbolic geometry.