Across the country, cities with mental arithmetic are Shanghai, Beijing and Guangzhou. Only education is a better mental arithmetic in Shanghai. This institution seems to be an enterprise of Shanghai Jiaotong University. The Oriental Pyramid is a better abacus mental arithmetic institution in Beijing. This institution has been doing abacus calculations for a long time and its strength is very good. There are also many affiliated schools. Guangzhou's abacus mental arithmetic is better than Aobo Education. Aobo Education has many branches in Guangzhou, and with the strong support of Guangdong Abacus Mental Arithmetic Association, its strength will not be bad. The above three companies are well-known companies I know, and the teaching quality is good. I hope it helps you.