You don't need to learn oral arithmetic in Hong Kong. Calculators are allowed to be used in mathematics in Hong Kong college entrance examination. If oral and written calculations fail, you can take them out and press a button.
Hong Kong, referred to as "Hong Kong" for short, is the People's Republic of China (PRC) Special Administrative Region. It is located in the south of China, east of the Pearl River Estuary, facing Macau across the sea in the west, adjacent to Shenzhen in the north and Wanshan Islands in Zhuhai in the south. The area includes Hong Kong Island, Kowloon, New Territories and 262 surrounding islands, with a total land area of 1 106.66 square kilometers.