This paper introduces the practical experience of training the calculation thinking of the senior grade students in primary schools by learning C++ programming to solve the typical mathematics problems. Starting from the essence of abstract computational thinking, this paper analyzes the abstract basis of C++ programming teaching; then, in the comparison and fusion between the core literacy of mathematics subject and the process of computational thinking, it forward the rationality of cultivating computing thinking around solving typical mathematical problems in primary schools; finally, the paper introduces how to develop a learning example of mathematical problem programming, which is suitable for the cultivation of primary school students' calculating thinking.