If you are particularly looking for NCERT, then i hope starting with class 6 NCERT maths you can build basics. All the NCERT books are available online. While solving the questions of NCERT if you have any doubts you can refer to solutions of NCERT . For aptitude it is better to practice more questions. Many books and online videos are available for aptitude preparation. Try to build calculation speed. Try to do mind calculations, so that you can improve the speed of calculation.

Hi...

R.S.Agarwal is the best book to improve your score in MAT. It has the basic formula and definitions .

This book will definitely help you to improve your quants.

All the best...