ab=a*b=(a*b)=(ab)，單獨拿出來表示的話我想應該沒人有意見，
但放在運算式中間就會產生一些疑慮，特別是運算式中有除法的時候，尤其這個題目中還是以數字代替變數，而我記得的習慣中，單純數字的運算式中是不會用省略乘法的方式表達，特別的是當中還有括號。
我記得我學過的數學讓我覺得這個題目中所得到的答案是0.6，當然，google與其他計算機得到15的答案其原因就是他們也認定這個運算式有問題，所以會自動把省略的乘法補回，使得運算式會成立，並用補回後的運算式運算，所以得到15這個答案。如果我這樣的說法成立，那google和其他計算機得到15這個答案我也覺得是正確的。只不過這樣又會回到前面對於「 乘法符號省略」這個名詞的定義的迴圈中了。

前面有很多網友說得很好，如果這個表示式用中文來說明的話，就很清楚了，
則：30/2(2+3)/5會解釋成：三十除以，兩倍的二加三，再除以五，則答案會變成0.6。
而：30/2*(2+3)/5會說成：三十除以二，乘以（二加三），再除以五，則答案會變成15。
若用中文的說法出題的話，答案應該很明確。不過這不太可能當作聯考的出題方式。所以在專業的考試場合，出題是否嚴謹必須仔細要求。而當一個問題可能出現兩個以上的答案時，就必須考慮這樣的出題是否需要修改。

所以，以這個題目來說，我真的覺得題目有問題，語意不清。

另，我不想和你討論，只是提出我的看法。
看你以前文章的風格，想必你的堅持必定根源於你的過去的教育與經歷，而且看你敘述的方式來說，想必你在其本科專業上有其專長與努力。看你在78區討論事情的文章是一種樂趣，但和你討論的話是卻有一種得不到結果的感覺而已，
過於堅持的爭辯卻得不到結果，這並非討論的目的，只是爭一時的口舌之快，雖然現實生活中大部分爭口舌之快的人會比較有優勢，

最令我訝異的是，這問題在78區有超過300篇的回應之後還沒有離題，如果不是藍底白字的網頁設計的話，我真的以為我到別的論壇了。

以上是我的一點小感想，我不是數學本科的人，工數也是重修低空飛過，如果我的說法有問題的話，請指正。

你都是選自己想看的部份嗎？昏倒= =

要不要貼完整一點？？

Notation <----你知道這個字是什麼意思吧！？翻成中文叫做"符號、標記"
--------------------------------------------------------------------------------------------------------------------------------
Division is often shown in algebra and science by placing the dividend over the divisor with a horizontal line, also called a vinculum or fraction bar, between them. For example, a divided by b is written
a
—
b
This can be read out loud as "a divided by b", "a by b" or "a over b". A way to express division all on one line is to write the dividend, or numerator then a slash, then the divisor, or denominator like this:

a/b

This is the usual way to specify division in most computer programming languages since it can easily be typed as a simple sequence of ASCII characters.

A typographical variation, which is halfway between these two forms, uses a solidus (fraction slash) but elevates the dividend, and lowers the divisor:

a⁄b

Any of these forms can be used to display a fraction. A fraction is a division expression where both dividend and divisor are integers (although typically called the numerator and denominator), and there is no implication that the division needs to be evaluated further. A second way to show division is to use the obelus (or division sign), common in arithmetic, in this manner:

a÷b

This form is infrequent except in elementary arithmetic. The obelus is also used alone to represent the division operation itself, as for instance as a label on a key of a calculator.

大家看完以上的內容，應該可以知道以上所要表達的是什麼吧！！

就是介紹不同符號標記的除法表示法，及常見於什麼地方。

他們的意義都是相同的！！只是樣子不一樣而已。

沒想到這你也可以扯這麼久，還可以自己腦內補完。= ="


接著再來看看你強調的這句

The obelus is also used alone to represent the division operation itself, as for instance as a label on a key of a calculator.

是不是應該翻成

"這個符號也習慣被單獨用來表示其為除法運算，例如一個在計算器按鍵上的標籤。"

怎麼我翻的結果跟你的認知好像差很大！？？



最後一併幫你把" * "解決

MULTIPLICATION SYMBOLS
X was used by William Oughtred (1574-1660) in the Clavis Mathematicae (Key to Mathematics), composed about 1628 and published in London in 1631 (Smith). Cajori calls X St. Andrew's Cross.

X actually appears earlier, in 1618 in an anonymous appendix to Edward Wright's translation of John Napier's Descriptio (Cajori vol. 1, page 197). However, this appendix is believed to have been written by Oughtred.

The dot (·) was advocated by Gottfried Wilhelm Leibniz (1646-1716). According to Cajori (vol. 1, page 267):

The dot was introduced as a symbol for multiplication by G. W. Leibniz. On July 29, 1698, he wrote in a letter to John Bernoulli: "I do not like X as a symbol for multiplication, as it is easily confounded with x; ... often I simply relate two quantities by an interposed dot and indicate multiplication by ZC · LM. Hence, in designating ratio I use not one point but two points, which I use at the same time for division."

Cajori shows the symbol as a raised dot. However, according to Margherita Barile, consulting Gerhardt's edition of Leibniz's Mathematische Schriften (G. Olms, 1971), the dot is never raised, but is located at the bottom of the line. She writes that the non-raised dot as a symbol for multiplication appears in all the letters of 1698, and earlier, and, according to the same edition, it already appears in a letter by Johann Bernoulli to Leibniz dated September, 2nd 1694 (see vol. III, part 1, page 148).

The dot was used earlier by Thomas Harriot (1560-1621) in Analyticae Praxis ad Aequationes Algebraicas Resolvendas, which was published posthumously in 1631, and by Thomas Gibson in 1655 in Syntaxis mathematica. However Cajori says, "it is doubtful whether Harriot or Gibson meant these dots for multiplication. They are introduced without explanation. It is much more probable that these dots, which were placed after numerical coefficients, are survivals of the dots habitually used in old manuscripts and in early printed books to separate or mark off numbers appearing in the running text" (Cajori vol. 1, page 268).

However, Scott (page 128) writes that Harriot was "in the habit of using the dot to denote multiplication." And Eves (page 231) writes, "Although Harriot on occasion used the dot for multiplication, this symbol was not prominently used until Leibniz adopted it."

The asterisk (*) was used by Johann Rahn (1622-1676) in 1659 in Teutsche Algebra (Cajori vol. 1, page 211).

By juxtaposition. In a manuscript found buried in the earth near the village of Bakhshali, India, and dating to the eighth, ninth, or tenth century, multiplication is normally indicated by placing numbers side-by-side (Cajori vol. 1, page 78).

Multiplication by juxtaposition is also indicated in "some fifteenth-century manuscripts" (Cajori vol. 1, page 250). Juxtaposition was used by al-Qalasadi in the fifteenth century (Cajori vol. 1, page 230).

According to Lucas, Michael Stifel (1487 or 1486 - 1567) first showed multiplication by juxtaposition in 1544 in Arithmetica integra.

In 1553, Michael Stifel brought out a revised edition of Rudolff's Coss, in which he showed multiplication by juxtaposition and repeating a letter to designate powers (Cajori vol. 1, pages 145-147).

我要承認我前面說「教科書這樣寫是錯」的說法是錯的。
因為我那時只想到電腦程式裡 / 的意義。

但 wiki 也有寫了，除法只有「表示法」，只有÷才具有「單獨運算元」的意義。所以把 / 看成表示法中的分數符號，那就不會有 a/bc = a/(bc) 的爭議了。

這是我自圓其說的解釋啦。至少這符合廠商說法、教授說法、教科書寫法、wiki 資料、電腦程式運算方法，豈不是很完美？

google 計算機都算等於10...

實在不能接受是單純的bug，應該還有什麼問題

這個叫「標記法」，不好意思，我翻成表示法，可能不太正確。但絕不是你說的「符號」。

a/b 絕不叫一個符號，我想不需要我再解釋。

底下那句，你的看法確實與我差異甚大，也沒什麼好解釋。

補充一下，因為/在教科書上的表示有些矛盾，我才加上自己的解釋。

盡信書不如無書，我從參考資料和各種資訊，加上自己的想法，沒問題吧？

不然你來解釋一下，/ 完全等同除法符號的話，要怎麼圓廠商說法、教授說法、Google 算法、wiki 對乘法表示法的說法？

他們都是屁？

OK 啊，你要這麼說我沒意見啦。

難道引用文章一定要用英文嗎？

可不可以消化完後用幾句話打出來。

其實只要是長篇大論，重點應該就只有幾句話。

要考慮一下廣大網友的語言能力。包括我啦！

話別說太滿,否則錯了,終究還是要承認的!

不然,恐怕會被噹到地老天荒吧!!

網兄可以收工了,不用再翻書了啦!

這位網友，
(1) 我的書裡面並沒有勘誤表
(2) 他的頁碼就是 x
(3) 我並沒有說那些地方敘述錯誤，我是提供資訊給那些覺得 1/2a 一定就表示0.5a的人，有個賺錢的機會。
(4) 我不會Laplace, Fourier, 我教你 Bogoliubov transformation 你說好不好 ？