Japanese Abacus Use & Theory

The Japanese Abacus & Theory book is easy to follow, and gives the reader step-by-step directions on how to use it correctly while applying it to practical use. The imperfect numerical notation and scarcity of suitable writing materials in ancient times are presumed to have given rise to need for devices of mechanical calculation. While the definite origin of the abacus is obscure, there is some reason for believing that its earliest form reckoning table covered with sand or fine dust, in wh