The Mag.num core field model is a crucial component in understanding the Earth's magnetic field. It serves as a parent model for IGRF- and other field models. The model's accuracy is essential for various applications, including navigation and geophysical research. By analyzing the model's strengths and limitations, researchers can gain insights into the Earth's core dynamics and improve our understanding of the magnetic field's behavior. This research activity aims to investigate the Mag.num core field model's performance and its potential applications in geophysics.