If you know the chinese charcters for different numbers, you can tell wich year it is. Your coin says 4 10 9, that is year 49 after the revolution 1911, that is 1960. As it is the starting point of the republic, you won't find years after 38 on mainland China, when the communists had the republican Chiang Kai Chek and his followers to run away to Taiwan. The republican party kuomingtang continued it's republic at the Island with Chiang Kai Chek as head of state. Therefore Taiwan continues to use this timeline.