I want to list some prime numbers in Japanese but I'm not if the Japanese comma should be used when it comes to numbers. On Wikipedia, the western comma is used, which has made me confused and unsure of how to display these numbers.

Option A

enter image description here

Option B

enter image description here

  • 1
    i’ll make the same recommendation i make to my english speaking math students: look at how well written texts in mathematics are written, pick a style you like, learn it, and stick with it. my personal preference is option A. in a list environment, which is the case in option A, a lot of space would wasted by using the “Japanese comma” of option B. but in embedded text, the Japanese comma facilitates reading. so be mindful of the context. but start by looking at how professional mathematicians write math in Japanese and follow their lead.
    – A.Ellett
    Oct 1, 2020 at 3:23
  • 1
    and since matters of prime numbers is a favorite of number theorists, i’d recommend researching what you can find in japanese in this field: 数論.
    – A.Ellett
    Oct 1, 2020 at 3:25

1 Answer 1


It depends on which "context" (or "mode") you are in.

If you are writing a news article and trying to explain what primes numbers are within an ordinary Japanese sentence, you should be using Japanese style punctuation.

On the other hand, when you are writing an academic article or a math textbook, it's common to temporarily shift to "math mode", where Western style commas must be used. The Wikipedia article you saw has many examples of this.

enter image description here

The yellow parts are in the "(inline) math mode" (i.e., $n-1$ if you know TeX), so Western commas are used. Outside these contexts, Japanese commas are used.

The same can be said with regards to English words. If you are introducing one or two English nouns in an ordinary long Japanese text, the base text is still in Japanese, so you should follow the Japanese orthography and keep using Japanese commas. If you are citing a long English sentences, you should switch to English mode and use the English punctuation.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .