59707
I'm trying to develop an API to normalize Japanese numbers into arabic
numbers. Since I'm not familiar with Japanese numbers, there are three
questions for which I did not find an answer:

  1. How do we write negative numbers in kanji ? for example, what would be the syntax of _-1234_ ? Does one use the minus sign as in English, or some other sign like 負 ?
  2. For the decimal separator, I read many things, and the source do not have the same answer: some say that it can be as in English, so for example "三千2百２十.三" will be equal to "3220.3". Some other source say that the separator is "點" or "点" and hence "七十五點四〇二五" is equal to "75.4025". So should I support the three characters as decimal separator ?
  3. About the zero, which one is really used ? "零" or "〇" ?
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2018-06-25T07:04:59.297
59706
2018-06-25T11:06:46.723
30193
question
kanji
numbers in Kanji
I'm majoring in Computer Sciences and studying in Japan. Here are what I
normally hear them being used:

>   1. In Japanese, the term to describe the negative number or value in
> general is 負の数. However, when you are saying a specific number like -1, -2
> or -1234, we use マイナス1, マイナス2, マイナス1234 respectively.
>   2. Both 点 and 點 describe the decimal separator. However, the kanji 点 is
> being used more often since it is a modern Kanji whereas 點 is an old and
> out-dated kanji. Since you are developing an API to normalize it, you can
> opt to go for both with 点 being the default.
>   3. Kanji for zero is 零(Rei). That is correct but when we write it out,
> it's レイ or れい. In my class, both the lecturers and students tend to use
> ゼロ(loan words of zero) or マル(Maru, which as you wrote above, is 〇 but we
> don't convert it into a circle). We hardly use 零 unless you are writing
> about the history of something or someone else's name. It may be used in
> other field of areas but in programming and our daily life, hardly anyone
> writes Rei as 零. With that being said, there is a possibility Rei is being
> written as kanji on the computer as the computer provides the option to
> choose the Kanji.
>
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2018-06-25T07:37:41.367
59707
2018-06-25T07:37:41.367
30385
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answer
Kanji is no longer actively used to represent complicated numbers in most part
of our daily life, and it's not a suitable way to describe numbers in
technical contexts. [Kanji numbers are still used in vertical
writing](https://japanese.stackexchange.com/a/17450/5010). When people really
need to write negative fractional numbers in modern vertically-written
materials (e.g. novels and newspapers), `-43.05`, for example, will usually
look like this:

[![enter image description
here](https://i.stack.imgur.com/mbdYj.png)](https://i.stack.imgur.com/mbdYj.png)

Katakana マイナス indicates the number is negative, and a [centered dot ("中黒") is
used in place of the decimal
sign](https://en.wikipedia.org/wiki/Japanese_punctuation#Interpunct). (By the
way, 点 "ten" is the _reading_ of this sign, not the actual symbol you write.)
The pseudo-kanji `〇` is usually used in this context. This is a relatively
recent convention only used in vertical writing. The same thing written
horizontally (`マイナス四三・〇五`) looks pretty unnatural.

Lastly, even if you're interested only in positive integers, there are still
several ways to write them. Please see [my previous
answer](https://japanese.stackexchange.com/a/18296/5010).
CC BY-SA 4.0
2018-06-25T07:46:14.460
59708
2018-06-25T09:35:25.620
2018-06-25T09:35:25.620
5010
5010
59706
answer