<![CDATA[This case study is intended to explore the thinking process of the fifth-year students of different sexes in estimating arithmetic problems. Two students, one male and one female, belonging to the high achievers in a mathematics test were selected for the study and then interviewed, assigned to solve arithmetic problems, and finally asked to think aloud their thinking process. The study reveals that the thinking process of both the male and female subjects is in the form of accommodation as they approached the arithmetic problems by repeatedly reading the tasks. Though employing the same thinking process, in the planning stage, the male subject made use of rounding and compatible number strategies, whereas the female one used only rounding strategy. In implementing the plan, the male subject employed mental counting through assimilation, but the female one used algorithm through accommodation. In the evaluating stage, the male subject traced back his work through mental counting, while the female one utilized reverse operations. Penelitian ini ingin mendeskripsikan proses berpikir siswa laki-laki dan perempuan yang berkemampuan matematika tinggi dalam melakukan estimasi. Penelitian dilakukan di kelas V SD, dengan subjek satu siswa laki-laki dan satu siswa perempuan yang memiliki skor 75 ke atas dalam tes kemampuan matematika. Data dikumpulkan dengan wawancara, pemberian tes dan think aloud. Analisis dilakukan dengan menelaah seluruh data, reduksi data, pengolompokan data, kategorisasi, pengkodean, dan pemeriksaan kredibilitas data dengan triangulasi waktu. Hasil penelitian menunjukkan bahwa proses berpikir keduanya adalah akomodasi. Dalam membuat rencana, laki-laki menggunakan rounding dan compatible number strategy, sedangkan perempuan menggunakan rounding strategy. Dalam melaksanakan rencana, laki-laki berhitung secara mental melalui proses berpikir asimilasi, sedangkan perempuan berhitung menggunakan algoritma melalui proses berpikir akomodasi. Dalam mengecek pekerjaan, laki-laki menelusuri dengan berhitung mental, sedangkan perempuan menggunakan operasi balikan.]]>
