20:02
Maths Olympiade, Chine
18:24
Harvard University Entrance Interview Tricks| Brain Tester Math Problem| Can you solve this problem?
10:58
Japanese| A Very Interesting Algebra Olympiad Math| Brain Buster Math| √ab=10,√bc=20,√ca=30,a+b+c=?
16:23
Germany | A Nice Algebra Problem | Math Olympiad
10:00