There are several journals and publications that can provide valuable tips and resources for improving numerical ability in the UPSC Mathematics Optional subject. These publications aim to help candidates enhance their understanding and problem-solving skills in mathematics, which is an essential component of the UPSC examination. Some of the prominent journals and publications in this field include:

1. Mathematics Today:
- Mathematics Today is a popular monthly journal that covers various mathematical concepts and problem-solving techniques.
- It provides comprehensive coverage of topics relevant to the UPSC Mathematics Optional subject.
- The journal includes solved examples, practice exercises, and previous years' question papers to help candidates improve their numerical ability.

2. The Mathematics Educator:
- The Mathematics Educator is a peer-reviewed journal that focuses on mathematics education.
- It publishes articles, research papers, and teaching strategies related to mathematics.
- This journal can be beneficial for candidates preparing for the UPSC Mathematics Optional subject as it offers insights into effective teaching and learning methods.

3. The American Mathematical Monthly:
- The American Mathematical Monthly is a renowned publication that covers various aspects of mathematics.
- It features articles on mathematical theory, problem-solving techniques, and applications of mathematics in different fields.
- This journal provides a platform for mathematicians to share their research and knowledge, which can be beneficial for candidates looking to improve their numerical ability.

4. Mathematics Magazine:
- Mathematics Magazine is a publication that caters to a wide range of readers, including students, teachers, and professionals.
- It covers various mathematical topics and presents them in an accessible and engaging manner.
- This magazine can serve as a valuable resource for candidates preparing for the UPSC Mathematics Optional subject, offering insights into different mathematical concepts and problem-solving strategies.

In conclusion, several journals and publications focus on providing tips and resources to enhance numerical ability in the UPSC Mathematics Optional subject. These publications cover a wide range of mathematical topics, offer solved examples and practice exercises, and provide insights into effective teaching and learning methods. Candidates can refer to these journals to improve their understanding and problem-solving skills in mathematics, which can ultimately help them excel in the UPSC examination.