Flash Anzan — Free Online Speed Addition Trainer

Numbers flash. You add them. That's it.

Mental math
4 min
Hard

Flash Anzan is a mental addition exercise: numbers appear one at a time, and you enter their total when the sequence ends. HumanCalc has 15 levels with longer sequences, larger values and shorter display times. Begin with single-digit addition; you do not need an abacus to play.

Play Flash Anzan

How it works

1Digits flash one at a time, in the same spot.

2Add each digit as it lands — do not wait for the end.

3Type the sum. Three in a row levels you up.

How to play

1
Digits flash
A short series of numbers appears one at a time in the same spot on screen.
2
Keep a running total
Add each number to a running total. For 3, 5 and 2, think 3 → 8 → 10 rather than trying to remember the entire list.
3
Type the sum
Enter the total when prompted. One correct sequence advances you through the early levels; from level 4, two consecutive correct sequences are needed. Two consecutive mistakes lower the level.

What it trains

Compute fast without writing anything down. Research on expert abacus users describes visual-spatial strategies for remembering digits. This browser exercise practices sequential addition; it is not a full abacus course or a test of those research findings.

Practice focus: Mental math
Based on: Hatano & Osawa, 1983

Research background

Hatano & Osawa (1983): Digit memory of grand experts in abacus-derived mental calculation

These sources describe related tasks or concepts. HumanCalc adapts them for browser practice; a game score is not a clinical result.

Leaderboard

Weekly season resets every Monday. Scores show as Lvl 5.

Leaderboard

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Questions

How fast do the numbers go?

Level 1 shows a new number every 1,500ms. Level 10 uses about 729ms and level 15 uses 300ms. A brief blank separates numbers, so a repeated digit appears as two flashes. Sequence length grows from 3 to 15 numbers.

What's a good level to reach?

Choose a level where you can follow the sequence and check your answer. Compare your own results at the same settings; HumanCalc has no verified population average for these levels.

Do I need to know how to use an abacus?

No. You can play using ordinary mental addition. Soroban and mental-abacus techniques are separate skills that you can study if they interest you.