Flash Anzan
Numbers flash by one at a time — add them all in your head.
How to play
A short countdown, then a run of numbers flashes on screen one after another. Add them together in your head as they go, and when the run ends, type the total and tap ✓. Get it right and the next round flashes one more number than the last. Get it wrong and the run ends — your score is the most numbers you managed to add in a single round.
Choose 1-digit numbers to start, and pick a speed you can just keep up with. As you improve, add a digit or turn up the speed.
What is Flash Anzan?
Flash Anzan (フラッシュ暗算) is a mental-arithmetic drill from the world of the soroban, the Japanese abacus. Expert practitioners can add a dozen three-digit numbers flashed in under two seconds by picturing the beads moving in their mind. You don't need an abacus to benefit — the exercise of holding a running total while new numbers keep arriving is a superb workout for working memory and mental addition.
Tips to add faster
- Keep one running total. Don't try to remember the numbers — only ever hold the sum so far and add each new one to it.
- Use friendly pairs. Numbers that make 10 (like 7 and 3) are quick to combine when you spot them.
- Stay relaxed. Panic wipes your working memory. Breathe, watch, add.
- Build up gradually. Master a speed at one digit before adding another; a solid slow base beats a shaky fast one.
What's a good score?
| Numbers summed (1-digit, medium) | Level |
|---|---|
| 3–5 | Getting started |
| 6–9 | Solid |
| 10–14 | Strong |
| 15+ | Excellent |
Frequently asked questions
Is Flash Anzan free?
Yes, completely free with no sign-up. It runs in your browser and your best score is saved on your device.
Do I need to know how to use an abacus?
Not at all. Flash Anzan comes from abacus training, but here you just add the numbers however you like — the benefit is in holding a running total in your head.
How does scoring work?
Each round you answer correctly adds one more number to the next round. Your score is the number of values in the largest round you summed correctly. One wrong total ends the run.
The numbers are too fast — can I slow them down?
Yes. Choose the Slow speed and 1-digit numbers to start, then increase the challenge as you get comfortable.