Short-Cut Math
Gerard W. Kelly, "Short-Cut Math"
ISBN: 0486246116, 0486131521 | 1984 | EPUB | 112 pages | 4 MB
Clear, concise compendium of about 150 time-saving math short-cuts features faster, easier ways to add, subtract, multiply, and divide. Each problem includes an explanation of the method, a step-by-step solution, the short-cut solution, and proof, as well as an explanation of why it works. No special math ability needed.