## My Fascination With The Abacus

### Basic Principles

#### Getting Started

In Japan, an unbelievable amount time and research has taken
place in order to determine the most efficient way to use an
abacus. This section contains the essentials on how to move the
beads in order to achieve the fastest performance from your
abacus.

The Basic principles listed here are based on the infamous book
*The Japanese Abacus Its use and Theory* by Takashi
Kojima.

This book is a must have for any budding abacus enthusiast, and
played an important role in fuelling the interest in the Japanese
Soroban in the west.

#### Moving Beads

It is best to sit at a desk or table, and lay the abacus flat.
When sitting in a soft armchair resting the abacus on a cushion,
gravity is not your friend.

Operate the abacus with your right index finger and thumb. The
left hand can be used to hold the abacus steady, or to mark a
position on a page of numbers. The other three fingers on the right
hand should be curled out of the way so that they do not interfere
with the beads. If you are using a soroban, reset the abacus by
tilting it forward so that all the beads fall to the bottom, place
it back on the table, then run your index finger under all the 5
unit beads to move them away from the bar. For some reason, this is
extremely satisfying.

Diagram 1 below shows the abacus with a value of 0.

Diagram 1. A Soroban, showing zero

The correct fingers are important in building up speed.

Use the index finger to:

- Move 5 unit beads up or down
- Move 1 unit beads down

Use the thumb to:

#### Values

A bead counts when it is pushed towards the bar. 1 unit beads
count when they are pushed up, 5 unit beads count when they are
pushed down. The diagram below shows a soroban that shows
123,456,789.

Diagram 2. A Soroban, showing 123,456,789

In the diagram, the rod designated to be the units rod is the
fourth rod from the right.

#### General Rules

There are six general rules described by Takashi Kojima:

- Move down a 5 unit bead and move up one or more 1 unit beads
at the same time.
- First move down one or more 1 unit beads, and then move up a
5 unit bead.
- Move down a 5 unit bead, and then one or more 1 unit beads in
quick succession.
- First move up one or more 1 unit beads, and then move up a 5
unit bead in quick succession.
- When adding, operate on the unit rod first, then operate on
the tens rod if there is a carry.
- When subtracting, operate on the tens rod first, before
operating on the unit rod.

Addition and subtraction are the building blocks to all other
types of calculation.

The next two sections describe how.