Hello,

As per the eligibility criteria laid out by ISI, only candidates who have been selected as INMO AWARDEES to participate in the International Mathematics Olympiad Training Camp in the present year or in any previous year, based on their performance in INMO will be directly called for interviews. however only holding merit of certificate of INMO or clearing maths olympiad by any organization doesn't guarantee about the confirmation of the admission test, though you will be required to fill in the application form, and with great academic record at 10+2 level along with any other relevant merit of certificate such as maths olympiad gives greater chances of admission,

you may go through the prospectus 2021 at https://www.isical.ac.in/~admission/Documents/IsiAdmission2021/ISI-Prospectus-2021.pdf and the selection policy at https://www.isical.ac.in/~admission/Documents/IsiAdmission2021/Selection-Policy-2021.pdf to know more details regarding this,