Mental Arithmetic Addition and Subtraction task book, Part 1 - Elementary Mental Arithmetic Addition&Subtraction task book, Elementary. Each lesson contains exercises with single-digit, two-digit or three-digit numbers on this topic. Exercises are performed on time. Furthermore, task book contains exercises for drawing with two hands at the same time. At the end of the book is the final test. Task book can be used both in group and individual classes with a teacher of mental arithmetic, as well as in self-studing of mental arithmetic at home. This Task book should be used together with the book "Mental Arithmetic Addition&Subtraction Rules", an Abacus (Soroban calculator) and Online trainer www.indigomental.com In this case, training will be effective.