Hello dear

As you must have passed the CBSE class 12 board exams with basic math and if you want to change it into standard math after the declaration of result you have to do some process and CBSE allowed to do this on some conditions for switching basic math to standard math I student need to pass the standard math in compartment examination which is conducted by CBSE and after passing the standard math examination in the compartment examination you will be able to study mathematics in higher classes of standard mathematics.

Hope this help!

Thank you!