Accessing a study group or discussion forum for the UPSC Mathematics Optional subject exam can greatly enhance your preparation and provide a platform for collaborative learning and sharing of knowledge. Here's a detailed explanation on how to get access to such study groups or forums.

1. Online Platforms:
- Join EduRev: EduRev is an online learning platform that offers study materials, practice questions, and discussion forums for various subjects, including UPSC Mathematics Optional. It provides a community of aspirants and experts who can help you with your queries and provide valuable insights.
- Search on Reddit: Reddit is a popular online platform with various communities (subreddits) dedicated to UPSC preparation, including Mathematics Optional. Join relevant subreddits and actively participate in discussions to connect with like-minded aspirants and gain access to study groups.

2. Social Media Groups:
- Facebook Groups: Search for UPSC Mathematics Optional groups on Facebook, where you can find aspirants who are preparing for the same subject. These groups often have study materials, discussion threads, and study group opportunities. Active participation in these groups can help you access study groups or discussion forums.
- WhatsApp/Telegram Groups: Join UPSC Mathematics Optional preparation groups on messaging platforms like WhatsApp or Telegram. These groups are created by aspirants or coaching institutes and provide a platform for discussion and sharing of study materials.

3. Coaching Institutes:
- Enroll in a Coaching Institute: Many coaching institutes offer UPSC Mathematics Optional coaching programs. These institutes usually have dedicated discussion forums or study groups for their students. Joining such coaching programs can provide you with access to study groups and discussion forums facilitated by experienced faculty and fellow aspirants.

4. Local Study Groups:
- Connect with Local Aspirants: Reach out to fellow UPSC aspirants in your locality who have opted for Mathematics Optional. You can find study groups by networking with them through coaching centers, libraries, or through online platforms. Local study groups can provide a more personalized and focused learning environment.

5. Offline Study Circles:
- Join Study Circles: Look for study circles or groups in your city that focus on UPSC Mathematics Optional. These study circles are often formed by serious aspirants who meet regularly to discuss concepts, solve questions, and share resources. Participating in these study circles can help you connect with peers and access discussion forums.

Remember, while accessing study groups or discussion forums, actively contribute, ask questions, and share your knowledge. Such engagement will not only help you gain access to these platforms but also maximize the benefits of collaborative learning and exam preparation.