You're eligible to appear for the CUET UG exam, even if you're awaiting the results of your improvement exam in Mathematics.The CUET UG eligibility criteria require you to have passed Class 12 or an equivalent exam from a recognized board, which you've already done in 2024.

However, to be eligible for admission to central universities like DU or BHU, you'll need to meet their specific eligibility criteria, which may include minimum percentage requirements in your Class 12 exams. For example, DU requires a minimum of 50% marks in aggregate for general category students.

When filling out the CUET UG application form, you should enter the marks you obtained in your Class 12 exams, including the marks you secured in the improvement exam, if available.If your improvement exam results are not declared yet, you can enter your previous marks and update them later, if needed.

To confirm your eligibility and the specific requirements for your desired course and university, I recommend checking the official websites of DU, BHU, and other central universities, as well as the CUET UG information bulletin.