French numbers to words converter (JavaScript)

This package converts numbers to their written forms in French language

The Rules

The units

less than 16 follow no rules but each has a specific name.”zéro”, “un”, “deux”, “trois”, “quatre”, “cinq”, “six”, “sept”, “huit”, “neuf”, “dix”, “onze”, “douze”, “treize”, “quatorze”, “quinze”, “seize”(from 0 to 16)

The tens

as French up to 60, or using Belgium-French (septante, huitante, nonante), up to 90, follow the same pattern.

“dix”,
“vingt”,
“trente”,
“quarante”,
“cinquante”,
“soixante”,
“septante”,
“huitante”,
“nonante”(from 10 to 90)”huitante” could also be “octante”. In French from France, the pattern change at 70:
70 = 60 + 10 = “soixante-dix”
80 = 4 * 20 = “quatre-vingts”
90 = 4 * 20 + 10 = “quatre-vingt-dix”

Numbers from 22 to 29, then 32 to 39 …

22 = 20 + 2 = “vingt-deux”, with a dash in between From 17 to 19, it follows this rule
17 = 10 + 7 = “dix-sept”

Numbers ending with 1:

The rule is the same as above, but with “-et-” which means “and” instead of “-“:

21 = “vingt-et-un” Before 1990, the writing was “vingt et un” but since the 1990 simplification reform, all words used for numbers are joined-up with dashes.

Numbers after 70 and 90

74 = 60 + 14 = “soixante-quatorze”
77 = 60 + 17 = 60 + 10 + 7 = “soixante-dix-sept”
95 = 4 * 20 + 15 = “quatre-vingt-quinze”
99 = 4 * 20 + 10 + 9 = “quatre-vingt-dix-neuf”

plurals of “quatre-vingt”:

80 : 4 * 20 = “quatre-vingts” → means 4 times 20 so 20 is plural, thus “vingts” ends with an “s”. But when it is not the ending of the word, the plural form disappear:
82 = 4 * 4 +2 = “quatre-vingt-deux”, without an “s” at “vingt”.

71, 81, 91

For some unknown reasons, 71 use an “-et-“, 81 and 91 use a dash.

71 = 60 + 11 = “soixante-et-onze”
81 = 4 * 20 + 1 = “quatre-vingt-un”
91 = 4 * 20 + 11 = “quatre-vingt-onze”

100 and more

One hundred is “cent”. One thousand is “mille”. The rule is joining this and the rest with a dash:

130 = 100 + 30 = “cent-trente”
1110 = 1000 + 1000 + 10 = “mille-cent-dix”

plurals of “cent” and “mille:

Like 80, 100 and 1000 can be plural if it ends a word and then takes an S: “cents”, “milles”

200 = 2 * 100 = “deux-cents”
3 000 = 3 * 1000 = “trois-milles”

When “cent” or “mille” is not ending the word, then it is not plural:

252 = 2 * 100 + 52 = “deux-cent-cinquante-deux”
2045 = 2 * 1000 + 45 = “deux-mille-quarante-cinq”
200000 = 2 * 100 * 1000 = “deux-cent-milles”, without S at “cents”, but with S at “milles”
180000 = (100 + 4 * 20) * 1000 = “cent-quatre-vingt-milles”, without S at “vingt”, but with S at “milles”

Github Repository

https://github.com/fjobeir/french-numbers-to-words

Installation

npm i french-numbers-to-words

Usage

const numberToWords = new FrenchNumbersToWords('fr'); // 'fr' for French or 'be' for Belgian French
numberToWords.convert(12345)
// The result is an object like this
{
  parts: [
    { number: 12, text: 'douze', unit: 'mille' },
    { number: 345, text: 'trois-cent-quarante-cinq', unit: '' }
  ],
  fullText: 'douze-mille-trois-cent-quarante-cinq'
}