Beadbay: the soroban
How to use a soroban: the first steps
On a soroban each rod is a place, the bead above the beam is worth five and the four below are worth one each, and a bead counts when it touches the beam. Set numbers from the biggest digit to the smallest, thumb for pushing lower beads up, first finger for everything else.
Try it
Press a Try button and follow the ghost beads. The page tells you when a move is the taught one.
The beads
The four beads under the beam are earth beads. Each is worth one. A bead counts when it touches the beam. Push three up with your thumb.
The bead above the beam is the heaven bead. It is worth five. Pull it down to the beam with your first finger.
The rods
The rod with the dot holds the ones. The rod on its left holds tens, then hundreds. Set a number from its biggest digit, left to right.
To read a number, go along the rods from left to right and say each digit: a rod with nothing on the beam is a zero.
Which finger
Your thumb pushes earth beads up. Your first finger does everything else. When the beads you need are there, just move them.
It feels slow for a day or two and then it is much faster than hunting with one finger, because each finger always knows its job.
Your first sums
When the beads you need are free, adding is just moving them. To add 2 to 5, push two lower beads up. To add 25 to 12, do the tens first, then the ones.
With bigger numbers, do the tens before the ones. Always work from left to right.
Clearing
To start again, swipe along the beam. Every bead goes back to rest.
What comes next
Sooner or later the beads you need are not there: you want to add 4 but only two lower beads are left. That is what small friends and big friends are for, and they are the heart of the soroban.
Questions
Which way round does a soroban go?
The single row of beads is at the top, above the beam, and the four beads to a rod are below it.
Where do the ones go?
On any rod with a dot. Most people use a dot towards the right so there is room for big numbers on the left.
Do I have to use my thumb?
It is the taught way: thumb pushes the lower beads up, first finger does the rest. It keeps your hand still and makes the moves quick.