Written by Thomas O’Conor Sloane(USA) 
Those Who Can Calculate Quickly Tend to Have Better Lives [EPUB ebook] 

Those Who Can Calculate Quickly Tend to Have Better Lives introduces the application of speed calculation in the field of mathematics in a novel and entertaining way. By establishing special relationships between numbers, it can perform faster addition, subtraction, multiplication, and division operations.The calculation methods introduced in "People Who Can Speed Up Their Calculations Will Not Have a Bad Life" can be applied to practical work to improve the speed and accuracy of calculations, and also allow readers to appreciate the wonderful arithmetic operations and exercise their logical thinking skills."Those who can quickly calculate will have a good life" teaches us how to quickly and accurately perform addition, subtraction, multiplication, and division in a novel, interesting, and practical way, making mathematical operations simple, fast, and efficient. The book is not obscure at all, but rather makes people feel like they can’t put it down and want to read it all at once to master all the effective and skillful calculation methods.This book is highly practical, interesting, and operable, and is worth reading.