The primary goal of this text is to replace the antiquated limitations of past and present engineering economics texts with modern computational tools: (1) The tedious use of limited tabulations of only eight of the 12 factors and the onerous error prone task of manually computing non tabulated factor values are eliminated by using the 12-Factor Calculator. It was designed by the author to easily and quickly provide the 12 factors of engineering economics for arbitrary values of i, g ( ), and six values N.  (2) Annual and present worth cost comparisons of industrial equipment with component replacements are easily made with the corresponding Worth Comparison  Calculators provided with the book. (3) The book contains a comprehensive treatment of multi-simple investments, which have not been discussed in the literature, and it provides a simple Step-by-Step procedure for determining if a multi-simple investment is a quasi-simple investment. That is, does it has one IRR and positive intermediate balances? Two numerical examples illustrate the use of this Step-by-Step.       (4) Previous presentations of non-simple investments are limited. They do not discuss the four classes of non-simple investments defined in the text and the corresponding Step-by-Step procedures for calculating their IRRs and balances.  Six numerical examples illustrate these Step-by-Steps.