32 simple tricks for quick mental calculations (Paperback) (ISBN-13: 9782917260982)

This short book is a collection of simple and easily grasped tricks to speed up your mental arithmetic. If you want to master them you should realize that to be used fully they need to be approached conscientiously, not mechanically. But it pays to master them as they will enable you to do calculations in your head without error, as with written calculations.