This Book covers whole of the 'O' Level syllabus and also most portions of other international similar syllabuses. For the convenience of students, a lot of examples are given which will help students to overcome their weakness in Mathematics (If they read the examples carefully). Keeping in mind the problems of students, the sums of exercises are given. E.g. it starts from simple sums gradually to difficult sums. The sums are equivalent to 'O' level examination papers. I. e. the sums will help students to solve 'O' Level examination papers at a greater extent. This book is divided into three parts. (i) Arithmetic and Trigonometry (ii) Algebra (iii) Geometry. I am grateful to many students, colleagues and friends who have assisted me to write this book.