Abacus is a Latin word that means 'sand tray' or 'sand board'. The abacus is a very ancient counting tool, possibly in use in Mesopotamia as long ago as 2000 BCE, and later in ancient Egypt, Persia and Greece. In its early form it was most likely a simple counting board or tray with a series of stones in grooves.
The ancient Greek abacus was a table or tablet with counters set into it. The earliest tablet found has been dated to around 300 BCE. The Romans adopted a similar abacus to the ancient Greeks, but later developed an abacus that used beads threaded on wires. This had the advantage of being much quicker to use.
The earliest evidence of the use of the abacus in China dates from around the 1st century CE. The Chinese abacus is known as a Suanpan. The Japanese adopted a similar design, called the Soroban.
In the workshop we are going to make a 5 + 2 abacus. This is an abacus where there are two beads above the dividing bar and 5 below it. This is the easier type of abacus to learn to use. The following 3 videos show basic operations on a 5 + 2 abacus.
This video demonstrates the use of the 4 + 1 abacus, which is slightly harder to learn because it involves complementary numbers. (There is also a good explanation here http://abacus.etherwork.net/pages.htm but it gets rather complicated as you go down the page!)
In Japan soroban training is taken very seriously and there are national competitions involving huge calculations. With practice calculations on an abacus can be faster than using a calculator. This video shows the sort of calculations that can be done.