This new book waswritten to provide students and operators with examples of a variety of different problems that will be encountered both on the job and for Grades 3 & 4 certification exams. The book is divided into four main parts: a review of significant numbers and rounding; two chapters on math followed by practice tests; and appendices. Each problem is presented with easily followed steps and comments to facilitate understanding. Included after each grade level are tests to help you determine where your strengths or weaknesses are. Appendices contain conversion factors, wastewater treatment equations, chemistry tables, depth-to-diameter tables, and flow charts of wastewater treatment processes.