note!

At some point before 1.0, this crate is likely going under a moderate re-write.

Korean Numbers

Converting a few different types to hangeul is supported:

• int
• money (f64)
• bigint
• str
• some math expressions

You can choose between Sino-Korean numbers (based on Korean's adopted Chinese characters, 한자), or Pure Korean numbers.

Example Usage

// Get Pure Korean Hangeul
assert_eq!("서른둘", hangeul_from_int(30, false));
assert_eq!("둘", hangeul_from_string(String::from("2"), false));

// Get Sino-Korean Hangeul
assert_eq!("백이십", hangeul_from_int(120, true));
assert_eq!("만 이천삼백사십오", hangeul_from_string(String::from("12345"), true));

// Get Sino-Korean Hangeul from a BigInt
assert_eq!("천극", hangeul_from_bigint(pow(BigInt::from(10), 51))),

// Get Hangeul from a math expression (Sino-Korean only)
assert_eq!("일 더하기 일", "hangeul_from_expression("1 + 1");

// Get Hangeul from money (an f64 which gets truncated to 2 places) (Sino-Korean only)
assert_eq!("일 점 일", "hangeul_from_money(1.1);

About Korean Numbers

Korean utilizes two number systems. One uses numbers that are purely Korean, the other uses numbers that are derived from borrowed Chinese characters (한자).

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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.

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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.

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Lastly, Korean number words are not spaced except for grouping words like 만, 억, 조, and upwards.

Pure Korean Numbers

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.

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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	ten
11	열하나	ten one
20	스물	twenty
21	스물하나	twenty one

1, 2, 3, 4, and 20 can be conjugated as well. todo: add conjugation rules here

Sino-Korean Numbers

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

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Sino-Korean number support in this program 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

Wikipedia lists even higher groupings, but at different exponents...

Power	Hangeul Grouping	Hanja
10^52 or 10^56	항하사	恒河沙
10^56 or 10^64	아승기	阿僧祇
10^60 or 10^72	나유타	那由他
10^64 or 10^80	불가사의	不可思議
10^68 or 10^88	무량대수	無量大數

Math Expressions

The following math expressions are supported. When doing math, Sino-Korean numbers are used.

pub enum KoreanMathOp {
    Add,
    Divide,
    Multiply,
    Subtract,
    Pow,
    Fraction,
    LessThan,
    GreaterThan,
    Equal,
    NotEqual,
    Log
}

Further Reading

0. Korean Numbers
1. Big Korean Numbers
2. Wikipedia - Korean Numerals
3. Korean Numbers Reference

Todo

• add conjugations for pure korean numbers
• Add counter enum and mappings
• Add API fn to get a counter for a kind of term
• Add counter information in README