Introduction:
The physics section of the JEE Main exam is a challenging part that requires a deep understanding of concepts and their application. While it is generally recommended to use pen and paper to solve the problems, it is possible to solve the physics section without them. However, it requires a certain level of expertise, practice, and mental calculation skills.

Methodology:
Here's a step-by-step approach on how to solve the physics section of the JEE Main exam without using pen and paper:

1. Understand the problem: Carefully read the problem statement and identify the required concept and formula. Visualize the scenario in your mind to better understand the problem.

2. Identify the given information: Extract the given numerical values, units, and any other relevant data mentioned in the problem. Mentally note down these values to avoid confusion during calculations.

3. Apply the relevant formula: Use your knowledge of physics principles and equations to apply the appropriate formula that relates to the given information. Mentally substitute the values into the formula.

4. Mental calculation: Use mental calculation skills to perform the necessary arithmetic operations. Break down complex calculations into simpler steps and perform them mentally. Utilize estimation techniques to get approximate values quickly.

5. Unit conversions: If needed, convert the units of the given values and the final answer to ensure consistency. Mentally perform the unit conversions by applying the appropriate conversion factors.

6. Check for reasonableness: After obtaining the answer, mentally assess if it is reasonable and falls within the expected range. This step helps to identify any potential calculation errors and correct them if necessary.

7. Practice: Regular practice is essential to improve your mental calculation skills and speed. Solve a variety of physics problems without using pen and paper to enhance your proficiency.

Conclusion:
While solving the physics section of the JEE Main exam without using pen and paper is challenging, it is possible with practice and expertise. By understanding the problem, identifying the given information, applying the relevant formula, performing mental calculations, and checking for reasonableness, you can successfully tackle the physics problems in the exam. Regular practice and honing mental calculation skills are key to mastering this approach.