You can use this tool to find out how to spell out numbers in French. At present, the tool works with whole numbers. You can enter both positive and negative numbers with a magnitude of up to one billion.
Numbers 019

Numbers 2069The number consists of a word for the multiple of ten plus optionally the number for the unit 19 from the list opposite. Names of the tens:
Tens and units are joined with a hyphen. So, 22 = vingtdeux, 45 = quarantecinq etc. If the unit is a 1, then the word et is inserted between tens and units: 21 = vingt et un, 31 = trente et un etc. Numbers 7079These continue on from soixanteneuf: 70 = soixantedix, 71 = soixante et onze, 72 = soixantedouze, 73 = soixantetreize etc. Notice the et in 71 which mimics the behaviour of 21, 31 etc. Numbers 8099The French for eighty is quatrevingts. Numbers 8199 consist of quatrevingt (minus the s) plus a number 119: 81 = quatrevingtun, 82 = quatrevingtdeux, 90 = quatrevingtdix, 91 = quatrevingtonze etc. Notice that none of these numbers use the word et. 
Hundreds
The French for '(a) hundred' is cent. Multiples of a hundred go deux cents, trois cents
etc with an s on cents. If the number is not an exact multiple of 100, then the number
representing the last two digits follows cent, which loses its s: 101 = cent un,
201 = deux cent un, 202 = deux cent deux etc. Notice that in French there is no word
for 'and' between the hundres and the tens/units, unlike in English, and that "a hundred" is just cent,
not 
ThousandsThe French for '(a) thousand' is mille. This word never adds an s, and there is never a word for 'and' between the thousands and the hundreds/tens/units. So: 1000 = mille, 2000 = deux mille, 2001 = deux mille un, 3079 = trois mille soixantedixneuf. 
The French for 'million' is million; 'a million' translates literally as un million. After the million comes the remainder of the number without any intervening word for 'and': 1000450 = un million quatre cent cinquante, 3008000 = trois millions huit mille. Note that millions does take an s in the plural. When followed by a noun, numbers like million must be used with the preposition de. So the French for 'a million people' is un million de personnes; the French for 'three and a half million trees' is trois millions cinq cent mille d'arbres.
Other large numbers (billion, trillion) behave the same way to million: they behave more like nouns, in that they are preceded by un or take a plural s, and are followed by de ... when used with a following noun.
Superficially, the names of large numbers such as billion, trillion are the same in French as in English. In practice, however, these names now refer to numbers of different magnitude in the two languages. French usage generally follows the 'long scale', in which a French billion corresponds to a million million.
Most English speakers in both the UK and US now use the 'short scale', in which a billion is a thousand million. The French equivalent of English 'billion' is milliard (whereas this word is now obsolete in English).
Bearing all this in mind, here are the names of some common large numbers in French. The numerals in the first column are in scientific notation, so 10^{6} means a one with six noughts (1 000 000):
Number  English  French 
10^{6}  a million...  un million de... 
10^{9}  a billion...  un milliard de... 
10^{12}  a trillion...  un billion de... 
10^{15}  a quadrillion...  un billiard de... 
10^{18}  a quintillion...  un trillion de... 
10^{100}  a googol...  un gogol de... 
All content and applets written by Neil Coffey. Latest update 9 October 2011.
(c) Javamex UK 2011. All rights reserved.