Rapid Math by Edward H. Julius (1992, Paperback)

This is an interesting book. It contains a number of tricks and shortcuts in everyday mathematics. To me, many strategies are effective and time-saving, but having been an abacus user since I was ten, I am not sure whether some of the tricks really saves time. I am only speaking for myself. This book, overall, is a fun book to read. No doubt, Mr. Julius has much to offer in this book.