# comma with number greater than 999: always used?

#### Thomas1

##### Senior Member
Hello,

I would like to learn if it's a common practice to put a coma in numbers like, for instance:
10,000
100,000
1000,000
10,000,000

I'm not sure about the last three; I inserted commas by the rule of thumb, I'd appreciate some rationale as to when you use them.

Tom

• You don't have to, it just makes them easier to read.
If I saw

1000000 ... I'd have to count the 0's.. but if I saw
1,000,000 - I'd instantly know it was 1million (two sets of three 0's)

In AE we always put commas after a third 0. Your 1000,000 should be 1,000,000. But when numbers get really big (i.e., more than twelve or so 0s) we use scientific notation.

Thank you.

Follow-up questions:
Do you insert commas into numbers consisted of various numerals (e.g. 123,987,367)?
Do you do the same with decimal fractions (I know you put a decimal point after 0)?

The answer to your question is, yes it is common practice. Yes it is after the third 0 you insert a comma.
To your other questions, yes.. if it's any number we also do it.

I have 34,567,674 hairs on my head.. etc etc.

We don't do it with decimal fractions, no.

Alex said:
I have 34,567,674 hairs on my head.. etc etc.
But only 34.567674% of them are gray!

In other words, when the number is not a decimal expression, we use commas as has already been suggested. When it is a decimal expression, no matter how far out the decimal is carried, we only use a single decimal point.

Of course, carrying out a number this far rarely occurs in everyday use, unless one is in a scientific or mathematic field, and then integers are commonly used.

Note that in many European countries the commas and points are used contrariwise: points between every three figures and a decimal comma. (This will probably change sooner or later because of the computers that use the anglo-saxon system.)

I guess the basic answer Thomas is that we insert a comma in any number above 999, then every three places thereafter. Consider it this way: the first comma seperates the hundred from the thousands; the second, the thousands from the millions, etc.

998
998
1,000
1,001 etc

999,998
999,999
1,000,000
1,000,001 etc

Hakro raised a very good point I forgot... it swaps in European countries, they use decimals instead of commas.

In AE we always put commas after a third 0. Your 1000,000 should be 1,000,000. But when numbers get really big (i.e., more than twelve or so 0s) we use scientific notation.

Yuck. I hate scientific notation. I would rather just read 10,000,000,000,000,000,000,000 .. haha

I believe that the international standard for decimalized measurements does not require a space or comma up to 9999. I don't know the reason for this, except perhaps to avoid having to put a comma in dates.

Since the US is stubbornly holding out against decimalization, I would guess that none of this applies over there.

The use of commas or decimals is also swapped in latin american countries.

A colombian would say 1.000.000,00 while in USA you say 1,000,000.00.

Interesting

The use of commas or decimals is also swapped in latin american countries.

A colombian would say 1.000.000,00 while in USA you say 1,000,000.00.

Interesting
Isn't the comma at the end used only for prices? Or would you also write 1.000.000,5 ?

I'm not quite sure. What I have experienced is that everytime I get in contact with somebody from Venezuela, Colombia, Uruguay....etc, they send me their numbers like that. (working with money basically).

Under other conditions I imagine they do the same, ex. if they are counting large volumes of merchandise, etc.

It would be nice if someone from Latin America can bring some light into how they use this.

I promisse I will contact my Uruguay resources and let you all know.

...and what if there is a range, like 1-2 thousand, do I still have to use the coma? Like: "each month I spend 1-2,000 euro on XXX" Many thanks for your reply!

...and what if there is a range, like 1-2 thousand, do I still have to use the coma? Like: "each month I spend 1-2,000 euro on XXX" Many thanks for your reply!

Most definitely.

...and what if there is a range, like 1-2 thousand, do I still have to use the coma? Like: "each month I spend 1-2,000 euro on XXX" Many thanks for your reply!
You don't have to use the comma. The comma separator is entirely optional, a matter of personal choice, unless you are working to a style guide that says otherwise.
It is, however, normal to use it.