Areas of knowledge tell us the categories of knowledge. People can define what knowledge is belong to which area. Mathematics is one of the areas of knowledge, which can well defined how we know knowledge. At the beginning of learning Math, students need to learn how to solve the simple equations. In which way, the answer is simple and accurate. That is logic. We need to use the correct logic to find out the knowledge. Theory is also the same thing. By forming a theory, we need to use the logic to predict, to make a hypothesis. In all the processes, they are required knowledge.