|The Salamis Tablet, 300 BCE|
In 1846, on the island of Salamis, a white marble counting board was discovered. The Salamis Tablet has been studied extensively, and one scholar has made a video of its proper use.
But when did abacus come to refer to the wooden frame with beads on wires? A reconstruction of a 1st century Roman abacus shows a board with grooves to keep the round beads in line. Visually, it resembles the abacus with which we are familiar. Gerbert of Aurillac (c.946-1003), one of the most influential scientific minds of his era, pushed the use of the abacus as a method of calculating much more swiftly than when using Roman numerals. He was able to promote its use even more when he became Pope Sylvester II.
The abacus in the form we think of it seems to come from China in the 2nd century BCE. Called a suanpán ("counting tray"), it was built with rods that held beads, 2 on an upper deck and 5 on a lower. Now called the "2/5 abacus," the two decks allowed the user to use larger numbers without adding 1+1+1+1, etc. Other versions had different numbers of rods, and different numbers of beads on them.
|Abacus showing 87,654,321|