eng Science and Education Publishing American Journal of Educational Research 2327-6150 2019-02-11 7 2 141 144 10.12691/education-7-2-4 EDUCATION2019724 article Doni Andriyan Zunaiedy andriyan_doni@yahoo.com 1 Edi Syahputra 1 Asmin Panjaitan 1 Post Graduate Program in Mathematics Education, State University of Medan, Indonesia This study aims to develop students 'mathematical combinatoric ability by using Nht type cooperative models, including (1) students' thinking processes on combinatoric abilities (2) Combinatoric abilities of students after Nht type cooperative learning and (3) levels of active student activity during the learning process. this is the class X-Multimedia2 SMK PAB 1 Helvetia as many as 30 students and the object of this research is the combinatoric ability of students. This study is a qualitative descriptive study. The instrument which used u consists of a combinatoric ability test, and an observation questionnaire of student learning activities. Data analysis uses the NHT (Numbered Head Together) model. Based on the data obtained data, the thinking process of students on combinatoric abilities after learning with cooperative models of NHT type is categorized into three categories, namely high, medium and low. (1) Students with high combinatoric abilities have conceptual thinking processes and are neat in completing combinatoric ability tests. Students with medium combinatoric abilities are having conceptual thinking processes but are less neat in completing combinatoric ability tests. Students with low combinatoric abilities in understanding problems using processes imperfect thinking, not concentrate and unable to use alternatives to answer and are not conceptual and neat. (2) Combinatoric abilities that are possessed by students of SMK PAB 1 Helvetia after Nht type cooperative learning are good. (3) The overall results of student’s presentations which is used during the teaching learning activities are in the se ideal time tolerance interval. http://pubs.sciepub.com/education/7/2/4/education-7-2-4.pdf Combinatoric ability cooperative of NHT type