dentaku

A simple web app that converts JavaScript BigInt-sized integers into Japanese kanji numerals.

Public site:

https://code4fukui.github.io/dentaku/

Japanese README:

README.ja.md

Features

• Converts arbitrary-size integers to kanji numerals using BigInt
• Uses embedded Japanese numeral units and SI prefix symbols
• Supports negative integers
• Allows comma-separated numbers such as 1,234,567
• Accepts SI symbol input such as 2M, 3.2R, and 1G234M567k890
• Provides utility buttons:
  • square
  • integer square root
  • multiply by 10
  • divide by 10 with integer division
  • maximum representable value
  • clear
  • copy result
• Shows the maximum value representable by the embedded numeral data

Data Sources

The numeral data is embedded in numconverter.js. It is based on:

• https://github.com/code4fukui/music-numeral-system/blob/main/numeral-system.ja.csv
• https://github.com/code4fukui/music-numeral-system/blob/main/numeral-system.en.csv

ES Module

The conversion logic is available from numconverter.js:

import {
  NUMERAL_SYSTEM,
  SI_SYMBOL_SYSTEM,
  bigintToKanji,
  parseSiInputBigInt,
} from "./numconverter.js";

const value = parseSiInputBigInt("3.2R", SI_SYMBOL_SYSTEM);
console.log(bigintToKanji(value, NUMERAL_SYSTEM));

Maximum Value

The app groups digits by 4 and uses the largest 10-power unit available in the embedded numeral data.

With the current data, the largest unit is 10^68 (無量大数), so the largest representable value is:

10^72 - 1

Run Locally

This is a static web app. Serve the directory with any local HTTP server:

python3 -m http.server 8000

Then open:

http://localhost:8000/

Opening the file directly may fail because the app uses ES modules, so using a local server is recommended.

Notes

The app does not fetch CSV files at runtime. Numeral data is bundled in the ES module.

SI symbol input is converted exactly as decimal text, not as floating-point math. For example, 2M means 2 * 10^6, 3.2R means 3.2 * 10^27, and 1G234M567k890 means 1,234,567,890.

When the input is a single SI-symbol value, the multiply by 10 and divide by 10 buttons keep the symbol in the input field. For example, 1Q becomes 10Q, and dividing 1Q by 10 becomes 0.1Q.

License

MIT