Japan is the world's calculator superpower. Rivalries between Japanese companies to make calculators ever slimmer, lighter and cheaper eventually propelled Japan to the top, and Japanese manufacturers have led sales of calculators for over 30 years in many countries. Before the calculator came along, Japanese people did arithmetic on the abacus, and then used hand-cranked calculating machines. Even now, in the age of PCs and tablets, calculators are still essential in accounting jobs.