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The purpose of this research is to know if there is or not the differences of students’ mathematical problem solving ability with CORE type of cooperative learning model and STAD. Method of this research using quasi-experimental research. Sampling technique using simple purposive sampling and got samples of 72 students in X grade at SMAN 6 South Tambun on even semester of 2017/2018. The instrument applied in this research is a test the ability of mathematical problem solving was committed first by validty test and reliability test for obtained the valid and reliable instrument. Precondition analysis in this research is normality with Shapiro-Wilk to obtained unnormal distribution instrument. The analyze of data obtained that 𝑍ℎ𝑖𝑡𝑢𝑛𝑔 =‒ 4,01 with ‒ 𝑍𝛼 = ‒ 1,96 and significance level of 0,05 that obtained the result 𝑍ℎ𝑖𝑡𝑢𝑛𝑔 = ‒ 4,01 < ‒ 1,96 = ‒ 𝑍𝛼, it demonstrated that 𝐻0 is rejected. In relation to that, this research conclude that there is the difference ability of students’ mathematical problem solving with CORE type of cooperative learning model and STAD.