Mentally Calculate It by Alabi Stephen

This book will show you how to round a few of the corners and cut through some of the traffic while dealing with arithmetic. The aim of this book, therefore, is to lower your dependence on a calculator and enhance your self-confidence at using your God-given devices (the mind and the brain) to compute simpler problems. It is, therefore, my deepest hope that this book will assist towards a better understanding of the basics involved and a deeper appreciation of the wonders of playing with and manipulating numbers.