How do I write or say a mathematical expression in Japanese?

This simple page is the result of a discussion on sci.lang.japan on how to say mathematical expressions out loud in Japanese. The information that came out of that discussion seemed too useful to waste, so I have prepared this page as a summary. Note:

there is no fixed way of saying things as there are a number of options and some people say things one way; others other ways;
the letters used in equations are pronounced using the alphabet names (see What are the names of the letters of the alphabet in Japanese?). Thus A is エー (e-), B is ビー (bi-), C is シー (shi-), X is エックス (ekkusu), Y is ワイ (wai), etc.
to differentiate between x and X, you say スモールエックス sumōru ekkusu and ラージエックス rāji ekkusu;
where used, "(" is かっこ (括弧) and ")" is かっことじる (括弧閉じる)
for + and - it is common to hear purasu (プラス) and mainasu (マイナス) instead of the native Japanese tasu (たす) and hiku (ひく). プラス and マイナス seem to be used more often for complicated equations.

Mathematical form	Japanese	Japanese - Romanized
$A + B = C$	Ａたす (足す) ＢはＣ	A tasu B wa C
$A - B = C$	Ａひく (引く) ＢはＣ	A hiku B wa C
$A \times B = C$	Ａかける (掛ける) Ｂ = Ｃ	A kakeru B wa C
$A / B = C$	Ａわる (割る) ＢはＣ	A waru B wa C
$A^B = C$	ＡのＢじょう (乗) はＣ	A no B jō wa C
$14X\over 5Y$	５Ｙぶん (分) の１４Ｘ	5 Y bun no 14 Y
$\sqrt A$	ＡのルートＡのへいほうこん (平方根) Ａのじじょうこん (自乗根) Ａのにじょうこん (二乗根)	A no rūto A no heihōkon A no jijōkon A no nijōkon
$\sqrt[3]{B}$	Ｂのさんじょうこん (三乗根) Ｂのりっぽうこん (立方根)	B no sanjōkon B no rippōkon
$x^2$	ｘのにじょう (二乗) ｘのじじょう (自乗) (the の can be omitted)	x no nijō x no jijō (the "no" can be omitted)
$f(x) = ...$	エフｘは ... かんすう (関数) エフｘは ... エフかっこ (括弧) ｘ	efu x wa ... kansū efu x wa ... efu kakko x
$f'(x)$	ｆダッシュｘｆプライムｘ	f dasshu x f puraimu x
$X!$	Ｘのかいじょう (階乗)	X no kaijō
$\|X\|$	Ｘのぜったいち (絶対値)	X no zettaichi
$\ln x$	ｘのしぜんたいすう (自然対数) エルエヌｘ	x no shizentaisū eru enu x
$\log_b x$	ログｂのｘ	rogu b no x
$dx/dt$	ｄｘｄｔ	d x d t
$\int (x² - 4x + 9)dx$	インテグラル (かっこ) ｘにじょうマイナスよんｘプラスきゅう (かっことじる) ディｘｘにじょうひくよんｘたすきゅうのインテグラルｘにじょうひくよんｘたすきゅうのｘせきぶん (積分)	integuraru (kakko) x nijō mainasu yon x purasu kyū (kakko tojiru) di x x nijō hiku yon x tasu kyū no integuraru x nijō hiku yon x tasu kyū no x sekibun

Acknowledgements

This page was originally one of Jim Breen's Mini-FAQ pages and is used with permission.

External links

A page on some common mathematical expressions from Japanese high school entrance exams.

If you have questions, corrections, or comments, please contact Ben Bullock or use the discussion forum / Privacy policy


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