算盤
Soroban
Traditional Japanese Abacus · Sliding Beads
Soroban Value
0
Zero
Target / Result
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💡
How Beads Move
Click upper bead → slides DOWN to divider (+5). Click lower bead → slides UP to divider (+1). Beads physically travel along the rod!
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Set a Number
Practice Operation
📜 History
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Step-by-step soroban bead moves
Enter numbers above and click Generate Steps.
0
Score
0
Streak🔥
0
Tried
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Secs
Press "New" to start!
⬆️⬇️
Bead Movement
- Upper bead slides DOWN to activate (=5)
- Lower beads slide UP to activate (=1 each)
- Active = touching the gold divider bar
- Max per column = 9 (5+4)
Set 7:
Upper bead ↓(5) + 2 lower beads ↑(2) = 7
➕
Addition (Tasu)
- Set number A — beads slide to position
- Add B digit by digit right → left
- 5-comp: +upper(5) −(5−B) lower
- 10-comp: +1 left col −(10−B) here
7+8=15
Overflow! +1 ten, −2 units → 15 ✓
➖
Subtraction (Hiku)
- Set number A on soroban
- Subtract B digit by digit
- Can't subtract? Borrow from left
- −1 left col, +(10−B) this col
15−8=7
Borrow: −1 ten, +2 units → 7 ✓
🧠
Complement Pairs
- 5's: 1↔4, 2↔3
- 10's: 1↔9, 2↔8, 3↔7, 4↔6
- Add 6 → +10(left), −4 here
- Add 4 → +5(upper), −1 lower
Quick ref
Add 7→+10,−3 | Add 8→+10,−2