Unlike Dyslexia children who faced difficulties in reading, Dyscalculia children have difficulties to understand numbers and math. Commonly, Dyscalculia children have issues to comprehend fundamental math concepts such as numbers, math operations, math symbols and math facts. Based on the current literatures, Dyscalculia signs are shown as early as 4 years old and appropriate interventions should be introduced in order to address their difficulties in learning math. Hence, this paper aims to report the findings obtained from effectiveness test of a mobile app called Calculic Kids©. In brief, Calculic Kids© is a mobile app specially customised for Malaysian Dyscalculia children. Quasi-experimental with pre- and post-test was performed in order to assess the effectiveness of Calculic Kids©. Two special education teachers and seven Dyscalculia children had participated in this study. The outcomes of this paper are on the usability and effectiveness in terms of knowledge enhancement. Descriptive analysis and one-sample t-test were performed from to the collected data. Based on the outcomes, it was noted that the Calculic Kids© is effective and has potential to be used in classrooms to improve the performance of Dyscalculia children in Malaysia. © BEIESP.