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Comment by MattSayar | Hacker News Reader

Somewhat off-topic, but this has been bugging me for years: for countries that use , instead of . in decimal numbers, how do they pronounce it? ie For the number 12.3 million, I could say "twelve point three million" or "twelve dot three million." For 12,3 million, do you say "twelve comma three million"?

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Here in Brazil we do say "twelve comma three million", even tho our word for "comma" is much harder to say than our word for "dot". But since everyone says it, it just sounds natural anyway.

Thanks for the insight. One more thing I can't figure out based on your reply is: how do you differentiate a decimal number from a list of numbers? For example, consider the list:

    12.3, 7.6, 3.2

It's easy to see the three different numbers. But otherwise, wouldn't it be:

    12,3, 7,6, 3,2

And how would you dictate that? "twelve comma three comma seven comma six comma..."?

Those would be grammatically correct around here, I don't think I ever seen anything like that in the real world. In actual math classes people will usually just put parenthesis around numbers: (12, 3), (7, 6), (3,2). Sometimes people will actually replace the comma for the dot to avoid confusion (there's no hard rule set on stone, as long as you're being clear, it's ok). Sometimes people will just space them differently like you did and hope that's clear enough. For dictating, I don't think anyone would dictate the commas between numbers, you would just space them when speaking "twelve comma three.... seven comma six".

If you think that's confusing. It's funny to know that we often also use the dot as a multiplication sign. So "12.3,7" actually means "twelve multiplied by 3.7" in english. Btw I'm curious, does other countries also use dot for multiplication or is it only us?

I'm used to seeing parentheses around numbers when talking about ordered pairs, or in the context of matrices and dot products, etc.

We do use dots to represent multiplication, but they're not on the "ground", they're mid-height, aligned with -

In the US using a dot like ⋅ (&sdot) is common.

We mostly used ; in math classes.

For a set: { 1,2; 3,5; -12,1 }

Calculators that are otherwise internationalised force the dot convention.

Yes, in Norwegian you would say "tolv komma tre millioner".

Of course if I'm speaking English I would use "point".

OK, I can get used to that if I had to. I don't understand how lists would work though, like I ask here: http://news.ycombinator.com/item?id=4257721

12.3 million in Russian is either less correct "12 и 3 миллиона" (12 and 3 million) or more correct "12 целых 3 десятых миллиона" (12 whole 3 tenth million, same as rational fraction).

Germans do that - we even call IEEE floats "floating comma numbers".

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