Hello student if you're willing to pursue course in which mathematics is mandatory subject then you should fill the roll number of this year and fill the application form as an appearing student or else if math is not mandatory in your preferred course which you're applying for then you can fill the roll number of previous year board examination.

I request you to please help me with your preferable course you're concerned about so that I can check and provide you the exact information.

Feel free to comment if you have any doubt

Good luck