Видео с ютуба Difficult Maths
Как математика становится трудной
The Simplest Math Problem No One Can Solve - Collatz Conjecture
Maths isn't hard. It's misunderstood.
The hardest problem on the hardest test
Only 1% Solved this Math Problem
Hard Problems The Road to the World's Toughest Math Contest
Why Is Math So Hard To Learn?
The unexpectedly hard windmill question (2011 IMO, Q2)
Top 6 Math difficult Questions Solved | math animation