Soroban for grown-ups — Unit 1: Reading and setting numbers

How the soroban shows a number

A soroban is a place-value machine. Each rod is one digit of the number: ones on the right, tens to their left, then hundreds and thousands. On every rod, the single upper bead is worth 5 and each of the four lower beads is worth 1, so one rod shows any digit from 0 to 9. A bead only counts when it is pushed against the beam.

Because each digit is a fixed pattern of at most five beads, a trained eye reads a rod at a glance instead of counting. That instant recognition is what later lets people do arithmetic on an imagined soroban (anzan).

Fingering and the unit dot

Traditional technique uses two fingers: the thumb pushes lower beads up, and the index finger pulls lower beads down and moves the upper bead both ways. The dots on the beam mark every third rod; choose a dotted rod as your ones rod and the dots to its left fall on the thousands and millions, like commas.

Always set numbers from the left. It matches how you read and say the number, and it is the order every calculation on the soroban follows.

Practice in this unit

You will set and read numbers up to five digits, clear the soroban, and finish with a flash round: a number appears for a moment and you type it. Most adults get through the unit in ten to fifteen minutes.