This study aimed to reveal the solutions of pre-service teachers to contextual problems related to number bases other than the base ten. Furthermore, it was intended to investigate which issues pre-service teachers discussed about their learning in the problem-solving process, including context, and about student learning in their future teaching practices. To achieve this, task-based interviews were held with 12 pre-service primary school teachers. During semi-structured one-on-one task-based interviews, some questions were asked to reveal preservice teachers' way of thinking about the problems and their reflection on the learning. In this context, data were obtained from the audio recordings and the students' written responses. Besides, researchers' notes are used as supporting documents for the validation of the data collection process. The main findings of the study revealed that context is a facilitator for preservice teachers in understanding number bases other than base ten. They gained insight and provided instructional explanations on how to teach the student by understanding the different number bases. Furthermore, context enabled preservice teachers to reflect on how to teach better by considering their own learning processes.