Training towards the development of the capacity of learners has become an inevitable trend of world education. Vietnamese education also emphasizes the comprehensive development of the capacity and the quality of students. In mathematics teaching, there are some notable capacities such as problem-solving capacity, cooperation capacity, capacity for using mathematical language, computing capacity and so on. In particular, the problem-solving capacity is very important to students because it helps them to solve problems not only in mathematics but also in practice. In this paper, we want to investigate the problem-solving capacity of students in primary schools through a problem required to solve in different ways. The results of the study showed that students had enough the problem-solving capacity to find out various solutions to the given problem.