How did people keep track of numbers before pen and paper were widely available?
How does addition and subtraction work if you don't have a handy written form for your numbers?
Say you can't read or write, but you can count - how do you add, subtract, multiply, or divide large numbers?
The answer to all these questions is . . . the abacus!

Abacus is a Latin word that has its origins in the Greek words abax or abakon (meaning “table” or “tablet”) which in turn possibly originated from the Semitic word abq meaning “sand”.

The abacus is a mechanical aid used for counting, it is not a calculator in the sense we use the word today. The person operating the abacus performs calculations in their head and uses the abacus to keep track of the sums, to carry, etc. The device evolved from a simple need to count numbers. Merchants trading goods not only needed a way to count goods bought and sold but also to calculate the cost of those goods. Until numbers were invented, these counting devices were used to make everyday calculations.

The evolution of the abacus can be divided into three ages: Ancient times, Middle Ages, and Modern Times. It is important to know abacus was known as counting board . Counting board is a piece of wood, stone or metal with carved grooves or painted lines between which beads, pebbles or metal discs were moved. The abacus is a device usually of wood (plastic, in recent times) having a frame that holds rods with freely-sliding beads mounted on them.

It is noted that the oldest surviving counting board is the Salamis tablet used by the Babylonians circa 300 B.C. Other that that, the Roman Calculi and Hand Abacus were used from circa 300 BC to circa 500 AD. During Greek and Roman times, counting boards were constructed from stone and metal.

In the Middle Ages, wood was the primary material from which counting boards were manufactured, the orientation of the beads switched from vertical to horizontal. As arithmetic( counting using written numbers) gained popularity in the latter part of the Middle Ages the use of the abacus began to diminish in Europe.

In modern times, abacus as we know today, appeared circa 1200 A.D in China. In Chinese, it is suan-pan. On each rod, this classic Chinese abacus has 2 beads on upper deck and 5 on the lower deck or referred as 2/5 abacus. The 2/5 style survived unchanged until about 1850 which time the 1/5 (one bead on the top deck and five beads on the bottom deck) abacus appeared.

Circa 1600 A.D., use and evolution of the Chinese 1/5 abacus was begun by the Japanese via Korea. In Japanese, the abacus is called soroban. The ¼ abacus, a style preferred and still manufactured in Japan today, appeared circa 1930. The 1/5 models are rare today and 2/5 models are rare outside of China .