These new and well-researched post Basic Education Mathematics for Senior Secondary Schools are based on the revised curriculum as developed by the Nigerian Educational Research and Development Council (NERDC). In line with the broad objectives of the Federal Government of Nigeria to promote entrepreneurial skills in a global world that has become highly competitive, this new curriculum is structured to emphasise such relevant topics as Capital Market Investment, Stocks and Shares from a purely mathematical viewpoint. Accordingly, five broad thematic subjects, such as Number and Numeration, Algebraic Process, Geometry, Statistics, along with such other topics as Logarithms, Equations and even Basic Theorems have been approached from entrepreneurial dimensions. In Book 3, in compliance with the curriculum and still within the same thematic structure stated above, students are introduced, among other things, to introductory calculus as a prelude to more advanced calculus in their future studies. In each of the titles, the chapters begin with a reproduction of state objectives, followed by a brief revision of previously covered ground and then broad definitions of the topic of study. Thereafter, mathematical examples are presented, with solutions and methods for arriving at such solutions explained. Each chapter ends with extensive revision exercises, usually taken, especially in Book 3, from past examination questions. In preparing the series, our collective experience as serving school and college teachers came into play. The special training seminar where modalities for manuscript preparation were outlined, style of writing defined and the essence of focusing primarily on the Nigerian experience and background outlined, came in quite handy. The format and presentation of the book should enable students to benefit greatly from the subject matter.