How to play
Flash Anzan for Beginners: How to Practise Speed Addition
By HumanCalc · Published · 3 min read
Flash Anzan is sequential mental addition. A series of numbers flashes on screen, one at a time. Your task is to add them and enter the final total after the last number disappears. HumanCalc starts with three single-digit numbers and lets you practise without an account or download.
The useful starting skill is keeping a running total. You do not have to remember the whole sequence, and you do not need to know how to use a soroban. This walkthrough shows the rule before you add speed.
A complete three-number example
Imagine that 3, then 5, then 2 appear. Keep only the current total in mind as each number arrives. The number you type at the end is 10. After checking the answer, begin a fresh total for the next sequence.
Sequence: 3 → 5 → 2
- First number: keep 3.
- Second number: 3 + 5 = 8. Keep 8.
- Third number: 8 + 2 = 10. Keep 10.
Enter 10 after the sequence ends.
What changes across HumanCalc's 15 levels?
The game changes three things: how many numbers appear, how long each remains visible and the range of values. These are HumanCalc settings, not standardized abacus grades. At higher levels, numbers can contain multiple digits. One correct sequence advances levels 1–3; from level 4, you need two consecutive correct sequences. Two consecutive mistakes lower the level.
| Level | Numbers per sequence | Display per number | Value range |
|---|---|---|---|
| 1 | 3 | 1,500ms | 1–9 |
| 4 | 6 | 1,243ms | 5–30 |
| 10 | 11 | 729ms | 100–999 |
| 15 | 15 | 300ms | 1,000–9,999 |
Try a short first session
If the sequence feels too fast, practise a few examples on paper first and then try the browser exercise. Repeating a level accurately is a useful practice choice; moving up is not the only goal.
- Choose level 1 and play one sequence to learn when the answer box appears.
- Add each number to your current total rather than keeping a list.
- Check whether a mistake came from losing a number, adding incorrectly or typing the answer.
- Repeat while you can follow the sequence. Use the starting-level controls to return to a manageable level.
Common mistakes and what to change
- Remembering the sequence but forgetting to add: replace the remembered list with a running total.
- Carrying the previous answer into the next sequence: reset your total before the first number.
- Choosing a level that is too difficult: lower the start level and check accuracy first.
- Judging your ability from one run: compare several attempts with the same settings.
How does this relate to mental-abacus training?
Hatano and Osawa studied digit memory in expert abacus-derived calculators. Their work describes specialized strategies; it does not establish that a few browser sessions produce the same expertise. HumanCalc is an addition exercise, so use it to practise the task and judge your own results.
