How to Say Math Stuff in Japanese

We have enjoyed a fairly mild December in Japan so far this year. However, starting today, the temperature will finally become 一桁ひとけた. The 桁 refers to columns or beams; in this case, it indicates the one’s column for numbers, which is a roundabout way of saying that the temperature will be under 10°C starting today. Brrr!

All this talk of cold temperatures reminds me that I don’t know how to do division. I mean, of course I can do division itself, even “long division.” Why do they teach us long division anyway? Why not “short division” so we can get the misery over sooner? But my point is that I did not yet learn how to say mathematical division statements out loud in Japanese.

That changed as of today, when I asked my resident native Japanese speaker for help. After reminding me that she hasn’t had to calculate square roots since high school, she provided the following translations for basic math features, the kind you might perform on a simple calculator (電卓でんたく).

Addition and Subtraction

The verb す, without conjugation, is used to add numbers together. For subtraction, use く, the same verb used to pull on a door handle.

  • 1 + 2 = 3: いちさんです。
  • 3 – 2 = 1: さんいちです。

Multiplication and Division

Multiplication uses the verb ける, although it is typically written using kana instead of kanji. Use the verb る when dividing numbers.

  • 2 × 3 = 6: かけるさんろくです。
  • 6 ÷ 3 = 2: ろくさんです。

Squares and Square Roots

If you search for “square root” in your English-Japanese dictionary, a whole bunch of complicated words show up. However, I’ve been assured that ルート is correct for mundane calculations. To take the square of a number, add の followed by 二乗じじょう.

  • √9 = 3: ルートきゅうさんです。
  • 32 = 9: さん二乗じじょうきゅうです。

Decimals, Fractions, and Negatives

When speaking decimals, use てん for the decimal point.

  • 25.03: じゅうてんゼロさん

Fractions appear reversed from their spoken English forms; mention the denominator first. The phrase ぶんの goes between the two fraction terms. Whole numbers paired with the fraction appear first, followed by と.

  • 2/3: さんぶん
  • 1-2/3 (that is, “one and two-thirds”): いちさんぶん

Negative numbers are the easiest of all. Simply start them with the English-derived word マイナス.

  • -34: マイナスさんじゅうよん

That should get you through basic calculator arithmetic. Now if you’ll excuse me, I really need to find somewhere warm to get away from these frigid 一桁 temps.

[Image Credits: uopicture/]


Tim Patrick

Tim Patrick is an author, software developer, and the host of Japan Everyday. He has published a dozen books and hundreds of articles covering technology, current events, and now life in Japan. Find his latest books at

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