See ISI is an examination which test your mathematical skills. Now if you have genuine interest in mathematics and if you are really enthusiastic about the subject then you will obviously crack it.

Now cracking the UG level examination can be a bit intermediating for some students as the syllabus of UG level for BMATH and BSTAT are not that usual 10+2 type. It has numerous things which are pure mathematics portions and are not taught in 10+2 for example, Combinatorics, Number Theory, Real Analysis (Basics) etc. Thus to crack the examination you have to be very sure about the syllabus. So read the syllabus very carefully and use the standard books for preparation like:

• Pre-college Mathematics
• An excursion of Mathematics
• Introduction to Real Analysis (Pearson)
• Elementary Number Theory by Burton
• Calculus of One variable by IA MARON(Arihant)

This is are the classic books for UG preparation of ISI. If you can cover this books then you will get the syllabus done. Now for practice you have a book with abbreviation 'TOMATO' which stands for Test of Mathematics at 10+2 Level. This contains all the previous year question papers. This is the books you should follow. Also you should keep your concepts very clear as in interview you will be asked conceptual questions so take care of it.

All the books mentioned above are available in any online website like Amazon Flipkart etc. You may not get the pdfs of this books but if you wish you can try it on internet.

To know more about ISI admission visit the link below:

https://www.careers360.com/exams/isi-admission-test

To get the official syllabus of ISI visit the link below (copy paste it on your browser):

https://www.isical.ac.in/~admission/IsiAdmission2017/Syllabus/BStat-BMath-Syllabus-UGA-UGB-2021.pdf

The syllabus for BSTAT and BMATH are the same.

If you want to download previous year question then visit the link below:

https://www.isical.ac.in/content/syllabus-and-qp

I hope this answer helps. All the very best for your future endeavors!