The marking system in the UPSC mains examination is structured around a total of 1750 marks, divided among nine papers. Each paper carries a specific weight, with the optional subject usually having a greater impact on final scores. The first two qualifying papers (Language and English) are crucial as they assess basic comprehension skills. The remaining papers, including the General Studies, Essay, and Optional, contribute directly to the final ranking. Candidates must achieve a minimum qualifying score in each paper, stressing the importance of comprehensive preparation.