Cardinal numbers - separation of words with a space beyond 100 000

Question

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?

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

RULE:
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)

RULE TO READ:

• 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:
1.001.001.001 = 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:

1.000.000.000.000 = un bilione (= mille miliardi)

1.001.001.001.001 = un bilione, un miliardo, un milione e milleuno

Hope this helps.