Online Abacus Simulator
Explore place value on a soroban with one upper bead and four lower beads per rod.
Represented value
Pink beads count toward the value. Click or tap a bead to move it toward or away from the middle bar. Nearby lower beads move together. Keyboard: use Tab to choose a bead, then Space or Enter to move it.
For 64 + 13: add one ten, then add three ones using +5 −2. The final value is 77.
The rightmost rod represents ones, then tens, hundreds, and so on. A lower bead counts as one unit of its column when moved toward the middle bar. The upper bead counts as five.
How to use the abacus
Select a bead with a pointer or keyboard to move it toward or away from the bar. Beads touching the bar count toward the displayed number. Reset clears every rod to zero.
Add 64 + 13 = 77
Show 64: an upper bead and one lower bead on the tens rod, plus four lower beads on the ones rod. Add one ten to show 74. To add three ones, add the upper bead worth five and remove two lower beads. The ones rod now shows seven, giving 77.
Use the guided 64 + 13 exercise above, then read the abacus guide for more explanation.