Short-Cut Math

by Gerard W. Kelly

Double or triple your calculation speed! Short-Cut Math  is a concise, remarkably clear compendium of timesaving tricks that provide faster, easier ways to add, subtract, multiply, and divide. 
  Easy to understand, get results quickly, save time, no special ability required!  Can you multiply 362 x .5 quickly in your head? Could you readily calculate the square of 41? How much is 635 divided by 2½? Can 727,648 be evenly divided by 8? If any of these questions took you more than a few seconds to solve, you need this book.  Short-Cut Math  is a concise, remarkably clear compendium of about 150 math short-cuts. By using the simple foolproof methods in this volume, you can double or triple your calculation speed — even if you always hated math in school.
 
Here's a sampling of the amazingly effective techniques you will learn in Adding by 10 Groups; No-Carry Addition; Subtraction Without Borrowing; Multiplying by Aliquot Parts; Test for Divisibility by Odd and Even Numbers; Simplifying Dividends and Divisors; Fastest Way to Add or Subtract Any Pair of Fractions; Multiplying and Dividing with Mixed Numbers, and more.

The shortcuts in this book require no special math ability . If you can do ordinary arithmetic, you will have no trouble with these methods. There are no complicated formulas or unfamiliar jargon — no long drills or exercises . For each problem, the author provides an explanation of the method and a step-by-step solution. Then the shortcut is applied, with a proof and an explanation of why it works .
Students, teachers, businesspeople, accountants, bank tellers, check-out clerks — anyone who uses numbers and wishes to increase his or her speed and arithmetical agility, can benefit from the clear, easy-to-follow techniques given here.
 

Genres: Mathematics, Nonfiction, Reference, Education, Science

128 pages, Paperback

First published January 1, 1969

Reviews

[Bram · Rating 2 out of 5]

Book with some tricks on how to add/substract/multiply/divide. Almost all the "tricks" are very, very basic, however, there were a few tricks that I didn't know before.

Even though several publishers sell this book, the ebook is freely available: http://archive.org/details/Short-cutMath

[Ben Gutierrez · Rating 5 out of 5]

I thought I knew a few things about calculating quickly. I suppose I did, but there are some that I never sussed out. Good examples are multiplying large numbers that are kind of close but not quite the same, multiplying numbers by teens, that sort of thing.

Not all of the proofs help build intuition. Visualizations would have helped. Since this book covers only addition, subtraction, multiplication, and division, you should be able to imagine arranging the numbers into rows and rectangles. This will make things clear and help you remember the rules.

Dover books all have issues with typesetting in ebooks, especially when there is math. This book is no exception. Be prepared to read carefully and imagine what the text is supposed to say.

[Kirk · Rating 4 out of 5]

Handy refresher on arithmetricks I learned in middle school, except casting out 9s. I can never remember that one. It's like using a baitcasting reel: I get mental backlash.

"Idiot's Guide: Speed Math" by Gaurav Tekriwal includes many of the same shortcuts. It also includes practice problems and Vedic tips for finger multiplication, powers of 2, 3, 4, and 5, and square and cube roots. If I were buying, it would be a better deal. But the library only carries this book, and "free is a very good price."

[Shu · Rating 3 out of 5]

It was fun getting quizzed on by my 8-year old daughter as she flipped through this short book while I was driving. It was also fun to spot the mathematical reasoning before arriving at the "Why it works" section at the end of each shortcut method. I would have enjoyed the book more if each chapter included a list of applicable math problems for one to test one's grasp of the concepts as well as to develop pattern recognition skills / affinity to numbers. Maybe an app or a game could help.

[Daniel · Rating 3 out of 5]

Some of the short cuts in this book were new and helped me save time when calculating, others are very common sense and basic. There are alot of short cuts however in some cases when you actually need to calculate things quickly, remembering the short cut and then running through the steps of the short cut would actually take longer than just doing a simple left to right calculation. This book could also use some more exercises for practice.

[Alain W · Rating 3 out of 5]

Good book to refresh your mental math ahead of an aptitude test.
I only wished the book had some exercises at the end of each chapter like secrets of mental math by A.T. Benjamin had, in order to fully apprehend the material.

[Daniel · Rating 5 out of 5]

A comprehensive, well structured book of techniques.

[Nabil Khalil · Rating 3 out of 5]

Very basic

[Kevin Demel · Rating 2 out of 5]

This book had a lot of hints about how to do math calculations quicker in your mind

[Jordan · Rating 3 out of 5]

Font is a nightmare and clearly from a 60s textbook but otherwise good info.

[Michael Pearce · Rating 5 out of 5]

Excellent maths book

I love reading and doing the maths in this kindle book, everything is laid out in a way that's easy to follow, I would recommend it to everyone.

[Abhiram Naik · Rating 4 out of 5]

Excited about it now the book will be insider

[Roger · Rating 3 out of 5]

Not a bad book. Worth a quick read to learn some basic math tricks.