Romaji is when you use the Roman alphabet to write out Japanese. I.e. you use "abc" instead of "あいうえお". Taking that one step further, what do you call it when you use "123" instead of "一二三"? My first thought was to call it "Roman numerals", but those are "I, II, III"...so would they be "Romaji numbers"? I realize usually we would just call them "numbers" in English (and in Japanese "数字"), but there is there a way to call them when there is a need to differentiate them?

The reason why I'm asking is because I was reading a book, and someone's age was written out in kanji numbers, and it got me thinking.

  • I suppose I, II, ... XIV etc. would be romaji?
    – Flaw
    Commented Aug 31, 2012 at 3:43
  • @Flaw: That makes sense to me, but that's never stopped me from being wrong ;) Commented Sep 1, 2012 at 21:34

2 Answers 2


They are known as Arabic Numerals, or アラビア数字 in Japanese. As you may notice, 1, 2, 3, etc. were developed by Indian mathematicians and did not originate from ancient Rome. Up until the 14th century Roman numerals were used, but were eventually abandoned in favor of Arabic Numerals.

  • The linked article sums it up nicely; I would also say "Arabic numerals" in English, so calling them the same thing in Japanese doesn't seem like a stretch.
    – AHelps
    Commented Aug 31, 2012 at 17:49

As Jesse Good said, Arabic numerals (0, 1, 2, …, 9) are called アラビア数字 in Japanese. Another name for them is 算用数字.

As an aside, numerals in kanji (一, 二, 三, …), loaned from Chinese, are called 漢数字 in Japanese. Roman numerals (I, II, III, …) are called ローマ数字.

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