Yes, it is highly recommended to revise the numerical problems and examples from previous year question papers for the following reasons:

1. Familiarity with question patterns:
By revising the numerical problems and examples from previous year question papers, you will become familiar with the types of questions that are commonly asked in the UPSC exam. This will help you understand the question patterns and prepare accordingly.

2. Practice and application of concepts:
Numerical problems and examples often require the application of concepts and formulas. By revising these problems, you can practice applying the concepts you have learned and improve your problem-solving skills. This will not only help you in solving similar problems in the exam but also in gaining a better understanding of the underlying concepts.

3. Time management:
The UPSC exam is known for its time constraints. By revising numerical problems from previous year question papers, you can improve your speed and accuracy in solving problems. This will help you manage your time effectively during the actual exam and increase your chances of completing the paper within the given time frame.

4. Identifying weak areas:
Revising numerical problems and examples from previous year question papers can help you identify your weak areas. If you find certain types of problems challenging or if you consistently make mistakes in certain concepts, you can focus on improving those areas during your preparation. This targeted approach will help you strengthen your overall understanding and performance in the exam.

5. Confidence building:
Solving numerical problems and examples from previous year question papers successfully will boost your confidence. As you become more comfortable with the question patterns and improve your problem-solving skills, you will feel more confident about your preparation and performance in the exam.

In conclusion, revising the numerical problems and examples from previous year question papers is a crucial part of UPSC exam preparation. It helps in understanding question patterns, practicing concepts, managing time, identifying weak areas, and building confidence. So, make sure to include this practice in your study routine.