Hey!

Following points will help in answering your query:

• Compartment means you are failed in one subject in 12th cbse for which re-exam will be held in july and you will get your fresh marksheet (with new marks in failed subject) after two weeks which will be same as of all other students.
• Failing in more than one subject will result in repeating one full year again.
• If you failed in one of the subject at 10+2 level then you need to sit for compartment exam and not for improvement exam. Clearing the compartment subject will give you the certificate to study in higher level that is after completion of 10+2 successfully you can go for a bachelor degree. But, you need to clear your compartment exam first with minimum 45% marks.
• In your case, you will have to repeat a year and give exams for all the subjects once again. After that, the fresh scores will be valid for calculation of 10+2 percentage for admission in different courses. Previous year's score will not be valid. No addition is done as you have mentioned.

Hope it helps!