The way subjects like maths are taught in East Asian schools tends to make a difference as to why students are so successful at the particular subject. Although teachers from the UK criticise this, the method rote memorisation and repitition practiced in Asian schools(specially Chinese and Indian) plays a huge part to the students success in math. East Asian Schools concentrate on basics and mental imprinting on the students. Although obsolete, this system works and schools are working to integrate it with Western methods of teaching.
Another reason why Asian students are good at math is the complicated writing systems and the stress of schooling systems to make children bilingual. Bilinguality makes it easier to understand algebras and calculus. The complcated writing systems of Asia such as the Chinese kanjis, Japanese kana and Indian Devnagri stress on strokes and discipline and were the original languages in which math began as a subject.