Zarxrax Wrote:One plus one equals two.
One minus 10 equals negative nine.
One times one equals one.
One divided by two equals zero point five (0.5)
Also, how do you read fractions, such as four fifths (4/5)?
In general, math phrases are tricky because pronunciations can vary depending on context and surrounding sentences. For example, "Because x = 2 and y = x+1, we have y = 3." is
Teacher in math class:
x = 2 かつ y = x+1 なので、y = 3 です。
(えっくす いこーる に かつ わい いこーる えっくす ぷらす いち なので、わい いこーる さん です)
But いこーる can be は, so, for example, "y = 3" reads わいはさんです if you see it as a sentence rather than an equation.
Argument in a math proof:
x = 2 かつ y = x+1 なので、y = 3である。
(えっくす いこーる に かつ わい いこーる えっくす ぷらす いち なので、わい いこーる さん である)
You never pronounce "=" は (wa) here. If you're going to use the result "y =3" to argue further in the same proof, となる is slightly better than である, though it's a matter of preference.
In an informal situation like explaining the answer to your friend, it can be:
xが2でyがx+1だからyは3
(えっくす が に で わい が えっくす ぷらす いち だから わい は さん)
The point is that if you see a math phrase as a sentence, you can apply Japanese grammar the way you do in normal speech so you can use は/が instead of いこーる. If you see it as an (in)equation, formula, and the like, you use math terms such as いこーる.
The examples you gave are usually taught before kids learn the mathematical concept "equal," so in normal context they are most likely:
One plus one equals two: 1足す1は2(いち たす いち は に)
One minus 10 equals negative nine: 1引く10は-9(いち ひく じゅう は まいなす きゅう)
One times one equals one: 1掛ける1は1(いち かける いち は いち)
One divided by two equals zero point five: 1割る2は0.5(いち わる に は れい てん ご).
Note that は as "=" is actually pronounced わ, i.e., it's the same as the は as a particle.
A faction x/y is read y分のx (わい ぶん の えっくす). If you replace the denominator and the numerator with numbers, you pronounce the numbers as they are, i.e., it's more like the "x over y" type of reading in the opposite order in a sense. So 4/5 is ごぶんのよん, and a half is にぶんのいち because it's 1/2. If the fraction is in a non-math text, you can use kanji for the number part, e.g., 五分の四.
As for 1.60, if you mean the number pronounced "won point six oh," which is slightly larger than 3/2, it's いってんろくぜろ or いってんろくれい.
Edit: Replaced "=" with ":" when it's not part of a math phrase to avoid confusion.
Edited: 2010-04-15, 10:55 pm