This research aims to describe of the students' argumentation ability in
completing the mathematical problem in terms of extrovert and
introvert personality types of students in SMP N 2 BMS on the material
lines and angles. This research belongs to descriptive qualitative
research. The subject of this research is the seventh grader (VII D) of
SMP N 2 BMS. The way to select the subject is by using purposive
sampling technique which consists of three students as the respondent
for each type. The technique of collecting data is questionnaire, test,
interview and docummentation. The technique of analysing data is by
dispalying reduction data and conclusion. The result of this research
shows that the written argumentation's students ability to complete the
mathematical problem of extrovert students' type have been able to give
the idea, have not been able to finish the problem, have been able to
mention a half of the data known, have not been able to utilize and have
been able to give another reason. Besides, the introvert students have
been able to do what the extrovert have not.