Online mental math trainer
Numbers appear one after another on the screen; your child adds (or subtracts) them in their head and types the answer. This is the “Flash Anzan” drill that Japanese soroban students practice every day – and that Kodomo Soroban Center students practice from lesson 6. Choose the digits, number of terms and speed that suit your child, then press Start.
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The tool runs entirely in your browser and sends no data anywhere. Settings and records are saved on your device.
How to practice properly
Flash Anzan only works when your child “sees” the beads in their head, not when they add by reading the numbers silently. So start very easy.
Start easy
1 digit · 3 numbers · 1 second. Easy enough to get 5 right in a row. The goal of the first week is the habit, not speed.
Go up one notch at a time
5 right in a row → increase the number of terms first (3 → 4 → 5), then the speed (1 → 0.8 → 0.6 s). Two digits only after Level 0 is finished.
5 minutes a day
Short and regular: 5 minutes after the worksheet. Note the highest level reached each week – children love “breaking the record”.
Why are Japanese children so fast at mental math?
In Japanese, anzan (暗算) means mental calculation, and Flash Anzan is a drill in which numbers “flash” up and disappear very quickly. There is no time to read “seven plus five is twelve” – the learner has to see the beads moving in their head. That is why Flash Anzan always comes after learning on a real abacus: the bead image comes first, speed later.
At Kodomo Soroban Center, children do mental math with small numbers from lesson 4 and Flash Anzan from lesson 6. This tool is the home version for continuing practice. If your child has not learned soroban yet, start with Learning soroban at home and the worksheets first; the tool becomes far more useful after a few weeks.
Where is your child?
- Just starting: 1 digit · 3 numbers · 1.5–1 s
- Finished Level 0 (KSC): 1 digit · 5 numbers · 0.8 s; start 2 digits · 3 numbers · 1.5 s
- Level 1: 2 digits · 5 numbers · 1 s, with subtraction
- Level 2: 2 digits · 10 numbers · 0.6 s; 3 digits · 3–5 numbers
- Competitions in Japan: 3 digits · 15 numbers · 0.3 s or less
Frequently asked questions
Can my child use Flash Anzan without having learned soroban?
Yes, with 1 digit, 3 numbers and 1.5 seconds – at that pace ordinary adding still keeps up. But to go further (more numbers, faster) your child needs the bead image in their head, which means learning soroban first. The tool is meant for extra practice after lessons.
How long should we practice each day?
5 minutes is enough, after the worksheet. Longer is not better; practicing every day is what matters. Stop while your child still wants to do more.
When should we raise the difficulty?
When your child gets 5 right in a row at a level. Increase the number of terms first, then the speed, and move to 2 digits only after Level 0 (direct addition and subtraction of 1–3-digit numbers on the abacus) is finished.
My child reads “seven plus five” silently. Is that a problem?
It is a sign that the speed is too slow or the numbers too easy – or that the bead image is not there yet. Try one notch faster; if the mistakes pile up, go back to the real abacus and practice setting numbers and direct addition and subtraction for a few more weeks.
Does the tool collect any information?
No. The tool runs entirely in your browser; settings and records are saved only on your device. We only count the number of answers (anonymously) to improve the tool.
Want real mental math? Start with a real abacus.
Classes of 3–5 at Vinhomes Gardenia (Hanoi); mental math from lesson 4, Flash Anzan from lesson 6. Free trial lesson.
