I have stumbled upon this link on the web: http://www.languagesandnumbers.com/how-to-count-in-italian/en/ita/.
I states: "Numbers are grouped in words of three digits, with the specific rule that a space is added after the word for thousand if its multiplier is greater than one hundred and does not end with a double zero (e.g.: duemilatrecentoquarantacinque [2,345], seicentomiladue [600,002], settecentosessantacinquemila duecento [765,200])."
I cannot find any confirmation in any Italian source. Moreover, in some reports of Italian authorities, I always see such complex numbers written as a single word, regardless of the "double zero" presence.
So, is this rule a nonsense?

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    I never heard of it, and I don't trust too much that web page (for instance, biliardo is “billiards”, the game, not 10^15), but you never know.
    – DaG
    Commented Oct 13, 2017 at 16:57
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    I had half an idea that we already covered something similar: here it is. More importantly, in a page of the Treccani website you can find a counterexample to that alleged rule: seicentocinquantaquattromilatrecentoventuno for 654,321.
    – DaG
    Commented Oct 13, 2017 at 17:02
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    @DaG See treccani.it/enciclopedia/… for “biliardo”. Apart from that strange and wrong rule on adding a space, the page seems fully correct to me.
    – egreg
    Commented Oct 14, 2017 at 6:56
  • @egreg: Thanks. I just find it strange that this word only appears in the Enciclopedia della matematica and in no other reference work, either by Treccani or other publishers (and I used to be a mathematician, so this is not some sort of prejudice).
    – DaG
    Commented Oct 14, 2017 at 8:48
  • @DaG I find it strange too. Personally I prefer American style “small scale”.
    – egreg
    Commented Oct 14, 2017 at 9:00

1 Answer 1


I have never heard that rule. In Italy we learn to read and write numbers this way:

Reading and writing 3 digits numbers:
100 = cento. It is an exception to the rule, you read “cento”, not “unocento”.
200 = duecento
300 = trecento
400 = quattrocento
430 = quattrocentotrenta
432 = quattrocentotrentadue
707 = settecentosette

if, after thousands, you have a 80 number, you have to delete one “o”:
180 = centottanta (not: centoottanta)
287 = duecentottantasette (not: duecentoottantasette)
if, after thousands, you have number 8, you have to leave the double “o”
708 = settecentootto
808 = ottocentootto

Reading and writing 4 digits numbers:

fist of all, in Italy we write 1.000 with a dot to group thousands, not comma.
Comma is used as “decimal point”, which separates decimal numbers from the whole number.
A number in standard form is separated into groups of three digits:
1.000 10.000 100.000 1.000.000

To read them, 1.000 is an exception to the rule, you read “mille”, not “unomila”
2.000 = duemila
3.000 = tremila
10.000 = diecimila
15.000 = quindicimila
100.000 = centomila
107.311 = centosettemilatrecentoundici
765.200 = settecentosessantacinquemiladuecento (your example)


  • you read the number at the left of the dot
  • you read the dot as “mila”;
  • you read the digits at the right of the dot. If you have only “zero” digits, you have to stop:

10.000 = diecimila (“10” = dieci + “.” = mila “000” = nothing to write or read)
199.000 = centonovantanovemila
199.007 = centonovantanovemilasette

Reading and writing 6 digits numbers:
1.000.000 = un milione 1.001.001 = un milione e milleuno

Reading and writing 10 digits numbers: = un miliardo, un milione e milleuno

507.935.399.011 = cinquecentosettemiliardi, novecentotrentacinque milioni, trecentonovantanovemila e undici

507.935.888.333 = cinquecentosettemiliardi, novecentotrentacinque milioni, ottocentottantottomila e trecentotrentatré

Reading and writing 13 digits numbers: = un bilione (= mille miliardi) = un bilione, un miliardo, un milione e milleuno

Hope this helps.

  • Good answer. It might be worth mentioning that sometimes one might also see an apostrophe (') used as a symbol to group thousands, especially in scholastic contexts.
    – Easymode44
    Commented Apr 12, 2019 at 13:10
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    @Easymode44 the apostrophe is only used in Swiss italian (e.g.: caffe.ch/stories/economia/…). In Italy a high dot is sometime used instead of the normal one, mainly in handwriting (I guess there's a specific Unicode character for it, but I'm not sure). Commented Apr 12, 2019 at 15:42
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    The apostrophe is never used as a separator, just the dot. Some publishers, however, shun the dot and prefer a half-space.
    – DaG
    Commented Apr 12, 2019 at 21:06
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    Personally, even though they are defined in the vocabularies, I'd avoid bilione (and its cousin trilione), since in my experience only misunderstanding and confusion come from them.
    – DaG
    Commented Apr 12, 2019 at 21:08
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    Wow, I'm impressed by the comments! I myself going to school in Rome have been taught (at least up until high school) to use apostrophes when separating groups of thousands. I might have had a quaint (or Swiss) teacher, I guess, nevertheless good point @OldManofAran, it is mainly in handwriting that one sees this.
    – Easymode44
    Commented Apr 13, 2019 at 12:18

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