There are several reliable sources where you can find previous years' UPSC Mathematics optional subject question papers. One such platform is EduRev, which provides a wide range of study materials and resources for various competitive exams, including UPSC. Here is a step-by-step guide on how to find previous years' UPSC Mathematics optional subject question papers on EduRev:

Step 1: Visit the official website of EduRev at www.edurev.in.

Step 2: On the homepage, you will find a search bar. Type "UPSC Mathematics optional subject question papers" in the search bar and press enter.

Step 3: You will be directed to a page displaying search results related to your query.

Step 4: Look for the relevant option that includes previous years' UPSC Mathematics optional subject question papers. It may be titled "Previous Years' Question Papers" or "UPSC Mathematics Optional Subject Question Papers."

Step 5: Click on the desired option, and you will be redirected to a page containing a collection of previous years' question papers.

Step 6: Scroll through the page to find the specific year or paper you are looking for.

Step 7: Once you have found the desired question paper, click on it to open and download it in PDF format.

Step 8: You can either download and save the question paper for offline access or view it online as per your preference.

By following these steps on the EduRev platform, you can easily access and download previous years' UPSC Mathematics optional subject question papers. These question papers can be immensely helpful in understanding the exam pattern, syllabus, and the level of difficulty of the questions asked in the UPSC Mathematics optional subject.

Please note: It is important to rely on trusted platforms like EduRev for accessing previous years' question papers to ensure their authenticity and accuracy.