Also, the attributes defined in the present step (S10) are not just for expressing a characteristic of one problem. The union of attributes for expressing characteristics of all problems included in the problem set or characteristics of all problems which can be made with regard to the subjects or chapters related to the problem set, can be defined. For this, in the present step (S10), a plurality of attributes can be defined.

A step for defining a plurality of attributes can consider subjects, chapters and so on of the problems included in the problem set. In case the problems included in the problem set are math problems, a plurality of attributes can be defined as a plurality of attributes related with math. For example, sequence, limit, similarity of figures and so on can be defined as a part of a plurality of attributes, but are not limited thereto.

The method for indicating characteristic of problem set according to present embodiment can be implemented, for example, by a system indicating characteristics of problems or characteristic of problem set described below. Therefore, the attributes defined in the present step (S10), can be indicated as corresponding codes. Here, the codes can be formed as combination of characters, numbers and so on, but are not limited thereto. For example, the code corresponding to the equation and inequality can be “C426,” and the code corresponding to the sequence can be “C382,” but is not limited thereto.

In some embodiments, with regard to each subject or each chapter, a plurality of attributes can be defined and saved in advance. In such a case, the present step (S10) can be skipped while implementing the method for indicating characteristic of problem set according to the present embodiment.