Connaissez-vous la date de votre anniversaire ? - Micmaths

From a channel Lumen includes in full: Micmaths is a math teaching channel by intent. It has structured school-level courses (the Pythagorean theorem series with history, statement, proof and worked examples; factorization; trigonometry), restoration and teardowns of calculating machines, and long explanations of real results such as the Conway knot and Hilbert problems. Even the playful formats, like balloon geometry or riddles, are built around a mathematical argument rather than spectacle. Titles are descriptive-but-fun rather than clickbait, and the only doubtful series is the 'SAV des mathématiques' viewer-feedback format, which is excluded by pattern as a precaution.

A 5-minute video from Mickaël Launay (Micmaths)'s catalogue; the title names its topic.

Video by Mickaël Launay (Micmaths), played through YouTube's embedded player.