To understand Quantum Mechanics (QM) and General Relativity (GR), key mathematical subjects include differential equations, linear algebra, and group theory for QM, while GR requires tensor analysis, differential geometry, and topology. Tensor analysis and differential geometry are essential for grasping the complexities of GR, with topology playing a significant role in various applications. While much of the necessary mathematics is often integrated into physics courses, additional study in these areas can enhance understanding and application in mathematical physics. Engaging with advanced topics like Hilbert spaces and category theory can also be beneficial for future research. A solid foundation in these mathematical concepts is crucial for a comprehensive understanding of both QM and GR.