Though generations of schoolchildren have cursed arithmetic, the world was a much more inconvenient place without it. Before the advent of modern arithmetic in the 13th century, basic calculations ...

To carry out their calculations, merchants in the early 13th century used an abacus or a system called finger reckoning. Commerce changed when Leonardo of Pisa — known today as Fibonacci — published ...

AN excellent way to see one’s own country, or one’s own century, is to visit another. While I was making just such a mental pilgrimage to the eighth century, a recent interest in unconventional ...