Dear Sir,

Firstly I will encourage the aspirant regarding ISI if he is really a notch in Mathematics.

ISI Admission test B.Math/B.Stat is a bit different than the mathematics we generally do in the +2 standard(especially the subjective part). First lets talk about Objective part- Objective part is more or less common to the the problems we generally do in +2 standards except it invokes some more thinking on the Calculus Part.Mainly the problems are from Calculus,Number Theory and Geometries. "Test of Mathematics at 10+2 Level" will be an ideal book for the preparation.Even there are a lot of past year papers available in the site www.isical.ac.in .Now coming to the Subjective Part- It involkes a really deep thinking and in depth ideas especially of the Number Theory.The time I sat for this my first question was a critical thinking applicaton of Pythagoras Theorem. There will be atleast 3 questions from Number theory,1 question from Recurrence Relation and 2 questions from Geometry."HIGHER ALGEBRA by Hall&Knight" or "HIGHER ALGEBRA by Barnard and Child" can be really handsome for the Number Theory.And for Geometries you can surf the websites like wolfram.Atlast "Test of Mathematics at 10+2 Level" is the best book to be referred to.

Hope I served you better