Mathematical creative thinking is an essential mathematical ability and must be possessed by every student to develop and master mathematics in learning. The purpose of this study was to determine the mathematical creative thinking ability of students in the material of geometric sequences and series of students of class XI IPA 3 SMA Negeri 1 Banda Aceh. The research design used is descriptive qualitative. The research subjects were 5 students who represented creative thinking skills in the creative category, quite creative and less creative. The instruments used are creative thinking ability test questions and interview guidelines. Data was collected through creative thinking ability test questions and interviews. The research data were analyzed through 3 stages, namely data reduction, data presentation and conclusion drawing. The results showed that only one student had the ability to think creatively, which fulfilled the indicators of flexibility, fluency and elaboration. In addition, two students have the ability to think creatively enough where one student meets the indicators of fluency and flexibility, the other student meets the indicators of fluency and elaboration. Then two students have the ability to think less creatively with one student meeting fluency and one student not meeting any of the indicators. These results indicate that follow-up in learning is needed so that it is expected to be able to optimize mathematical creative thinking skills.
Keywords: Creative Thinking Ability, Geometric Sequences and Series.