The variability of students' skill in conjecture is one of the challenges math teachers have when teaching number pattern topics. This is demonstrated by the errors made by students when examining a case, categorizing it, searching for, identifying patterns, and formulating conjecture. Four students were identified as slow learners after a series of assessments. As a result, a technology that can be used as an aid (assistive technology) was required. This project intended to create a mobile learning-based application that can be an aid for students who struggle to learn, especially when it comes to understanding material about numerical patterns. This study employs a design-based research paradigm with four phases, including 1) requirements analysis of real-world issues; 2) problem-solving development; 3) design of mobile learning applications, and 4) reflections and documentation of findings. The design of mobile-learning application has been generated from this research, which can then be used to create mobile learning-based application product.