The soroban is the Japanese abacus that helps you do fast mental math. It has several columns (rods) separated by a horizontal bar.
- The bead above the bar is the heaven bead, worth 5.
- The four beads below the bar are the earth beads, each worth 1.
A bead counts only when it is moved toward the bar. Each column is a place value: ones, tens, hundreds… from right to left.
Key concepts
1 Value of a single column
Column value = (heaven bead if lowered ×5) + (number of raised earth beads). So the largest digit in one column is 9 = 5 + 4.
2 Representing numbers
To show 6, for example: lower the heaven bead (5) and raise one earth bead (1). Try the buttons below to see how numbers are formed.
Interactive examples
Pick an example, then press “Next” to see the solution step by step on the abacus.