Converts a string, {integer}, or BigInt to hangul output.
You can choose between Sino-Korean numbers (based on Korean's adopted Chinese characters, 한자), or Pure Korean numbers.
```rust // Get Pure Korean Hangeul hangeulfromint(30, false); hangeulfromstring(String::from("2"), false);
// Get Sino-Korean Hangeul hangeulfromint(600, true); hangeulfromstring(String::from("980"), true);
// Get Sino-Korean Hangeul from a BigInt hangeulfrombigint(pow(BigInt::from(10), 51)); ```
Korean utilizes two number systems. One uses numbers that are purely Korean, the other uses numbers that are derived from borrowed Chinese characters (한자).
A confusing aspect is that number groupings are done in terms of 4 zeroes, not 3.
In English, 100,000 is one hundred thousand: 100 * 1,000.
In Korean, it's 십만, or 10 * 10,000.
10 = 십 (in Sino-Korean) 10,000 = 만.
In English, 1,000,000 is one million. In Korean, it's 백만, or 100 * 10,000.
100 = 백. 10,000 = 만.
After 만, the next unique word for a grouping is 억, at 10^8. You can see all of the groupings this program supports below.
Lastly, Korean number words are not spaced except for grouping words like 만, 억, 조, and upwards.
Pure Korean numbers are only used for numbers 1 through 99. They mirror our twenty, thirty, etc, in that each tens increase has a unique word to memorize.
In real life, it's uncommon to use pure korean numbers over 50 or so.
To show the tens place, the place word comes before the number.
1 is 하나, 10 is 열, 20 is 스물 (in Pure Korean).
| Number | Hangeul | Literal |
| :---: | :---: | :---: |
| 1 | 하나 | one |
| 10 | 열 | one |
| 11 | 열하나 | ten one |
| 20 | 열하나 | ten one |
| 21 | 스물하나 | ten one |
Adding a number before a place word like 십, 백, 천, 만, etc, multiplies it. Adding a number after adds it.
3 is 삼, 10 is 십 (in Sino-Korean).
| Number | Hangeul | Literal |
| :---: | :---: | :---: |
| 13 | 십삼 | ten three |
| 30 | 삼십 | 3 tens |
Sino-Korean number support goes up to 10^51:
| Power | Hangeul Grouping | Hanja | | :---: | :---: | :---: | | 10^4 | 만 | 萬 | | 10^8 | 억 | 億 | | 10^12 | 조 | 兆 | | 10^16 | 경 | 京 | | 10^20 | 해 | 垓 | | 10^24 | 자 | 秭 | | 10^28 | 양 | 穰 | | 10^32 | 구 | 溝 | | 10^36 | 간 | 澗 | | 10^40 | 정 | 正 | | 10^44 | 재 | 載 | | 10^48 | 극 | 極 |
-- see todo