Yes , i had understand yoyr query regarding the isc board as i would like to give you brief about this as follows:

AnswerYes, you can appear for the ISC Examination in the subject Mathematics. ... You will have to give a written application to the Principal of the School from where you wish to appear for the ISC Examination , who will register you online for the entry to the Examination .

The passing mark for ICSE is 35 in each subject and for ISC it is 40. A student must pass in English and any other 4 subjects for ICSE and English and 3 subjects for ISC . No everyone don't pass. ... it is very difficult to fail in ISC