The Theory of Mental Arithmetic

This book introduces the fundamental concepts behind a new form of calculation, "Circlemaths". Being one of the original books written by Dr Taylor the actual techniques ("COT tables" and so forth) are largely outdated, however what is of tremendous interest is the clear no-nonsense approach to number along with insights into the philosophy which produced the number theory. Not many philosophical approaches can be utilized to produce simple arithmetical results, but this one does. The link between philosophy and number becomes clear as you read.