The best books to refer to for Mathematics are as follows:
BooksAuthor/Publisher Magical Book On Quicker MathsM. Tyra Quantitative Aptitude for Competitive ExaminationsAbhijit Guha and R.S. Aggarwal A New Approach to Numerical AbilityDhillon Group of Publications UPSSSC General Maths Chapter-wise Solved PapersYouth Competition Times Complete Arithmetic Book in HindiSharda Publication