30÷2（2+3）÷5＝？簡單算式難倒計算機

[l1212tyuuyt1]

小小一個算式 就可以測試出計算機的品質??

[mike2215969]

不是要先算掛號在算乘除加減嗎?

[LEGEND19891109]

对不起，刚才发的有点问题，运算符优先级是（），/，*，+，-­。我的理解是：如果算式是30÷2（2+3）÷5 乘号如果省略，计算器是否会将2与（2+3）中的运算符默认为'­·’点乘号来进行乘法运算，因为‘·’点乘号的优先级高于'/'­号因此得到0.6这个结果，而对于另外一个相对简单的计算器，‘­·’号也许并不是它的一个运算符号，因此2与（2+3）中的默认­符号是X号因此按照优先级于运算方向得出结果15。

[LEGEND19891109]

计算器（机）中运算符号的优先级依次是 （），*，/，+，-。运算方向是从左到右。那么这个算式30÷­2X（2+3）÷5先算（）得5，再算X得10，剩下的算式30­÷10÷5，运算符号拥有相同的运算优先级则遵循从左到右原则得­0.6.

[winonejay]

大學教授怎麼跟街友長得好像= =

[Wupirn]

其實前面是除號，後面括號前乘號不可省略。

[bhang0507]

因為先乘徐, 後加減

[jerry7145]

第一個學生講錯了 應該是30除以2才對(字幕沒打錯)

30除2=2除以30=15分之1

因為a/b a是被除數 b是除數

所以a被b除 b除a a用b去除

所以「除以」和「除」是不可搞混的

[jerry7145]

這是個錯算式 2和括號中間的乘號不可省略

[MrTomsmy]

那兩台我家剛好有一模一樣的計算機

好巧喔

那兩台當初買的時候貴死人了

[f3243097]

他計算機也太專業了吧  我手機內建的計算機也算15

[tingka100]

我是

30÷2 (2+3) ÷5

15x5÷5

=15

[JACK03999]

@edwincyy 由左到右 啦= =

30÷2（2+3）÷5

30÷2 * 5 ÷ 5

15 * 5 ÷ 5

75 ÷ 5

= 15

[aixc92]

@edwincyy

你沒事加個隱形中括號乾嘛呢??

可見你沒認真看影片

[hi89112]

on 9, 計0.6的計算機, 設計出來就是想方便不加括號的懶人, () 的"乘"就是設計作為跟著前一個數子分配做分子還是分母的乘數, X 的"乘"就是必定分到分子的乘數, 不懂用就不要說人家錯= = !

還有.........想清楚d, 無論做加減還是乘除, 加個括號不就好了, 清楚得來又方便查錯處= =

[waiisnotpk]

答0.6的...

是認為30÷2(5)÷5不等於30÷2x5÷5吧

其實是一樣的...

30÷2=15

15x5=75

75÷5=15

()等於x的...

[waiisnotpk]

這個問題發生很久啦

但網上一大班人說是0.6...集非成是

人家出來說是正確是15~那這人還堅持0.6是對

還拿出一堆驗證方法證明0.6是對的 (但一開始概念已經錯了)

最強的...大學教授出來說15才是正確

說0.6的還說大學教授讀屎的=.="真野蠻

現在又提出這問題~希望那些答0.6的人醒醒吧...

[yiling20058]

癡線，答案點會係15？先乘除後加減呀大佬

先乘

2x5 =10

再除

30/10/5 = 3/5 =0.6

[ching919]

@yiling20058

正常冇錯係先乘除後加減

但你係咪睇漏左個括號?

括號裏面既數先計,

30÷2（2+3）÷5

=30/2(5)/5,(5)/5約左

=30/2

=15

[noelyao]

既然将乘号省略左，应该就要将2(2+3)睇成一个项了吧。。。­

[dnin478]

應該是0.6ㄅ 我以前數學算還不錯 但是我出社會好久了 感覺對我沒幫助

[yinbyc]

有括號既數係一定要計先 30÷2(2+3)÷5 應該係=0.6,因為只要加番少少野係本身隱藏左既符號 你就明嫁啦 30÷2x(2+3)÷5 =30÷2x(5)÷5 =30÷10÷5 =0.6 咁點解 30÷2x(5)÷5係=30÷10÷5呢??? 係因為2本身係(5)係一齊 轉轉條題目 10a÷a(a)÷5a =10a÷a既2次方÷5a 所以會係2a÷a既2次方 重有電腦既計算都係=0.6, 你認為電腦會差過計算機??

[qqwe1017]

@yinbyc

乘除地位相等，所以得從左邊到右邊

[jackybb2]

@yinbyc 無錯!係先計捨號, 所以,答案係15! 因為 30÷2(2+3)÷5 =30÷2(5)÷5 =15(5)÷5 =75÷5 =15 系2同括號旁邊係有一個隱形嘅乘號! 所以,條式可以寫做30÷2x(2+3)÷5 如果你部電腦計到0.6嘅話, 你都係換個部電腦好啲喇!

[yinbyc]

@jackybb2 哦，明白晒,謝XD,岩岩都問左呀哥,用計算機/電腦要咁打(3­0÷2(2+3)÷5

[ggyygygy]

數字不在括號內就按照順序從左算過去吧

這個就是對自己太過有自信的錯誤(?)

[yiuhogun]

你去死la,你連讀小一都冇資格

我計過咁多年數,我而家中4,我都未見過可以咁計

有小小數學知識的人都知係計2（2+3）先la,姐係

30÷2(2+3)÷5 = 30÷2(5)÷5 = 30÷10÷5 =0.6

[s7916380]

報導的像 高階計算機不需要存在的一樣

給你一個電子學 電機學 光電的題目 你拿個200元計算機的按給我看阿

[s7916380]

蠢，電子計算機 記者你們懂個屁....

學電子的人 利用高階計算機的公式 快速解題 很正常

[594210]

這種題目應該不是模擬兩可吧！

括弧前的數字帶到括弧裡，兩者中間又沒符號，

這種公式應該是最基本的不是嗎！？



[piscoau]

@594210 說真的,我讀數學讀了這麼多年,還是第一次見到這種模棱兩可的算­式= =

明顯是出題者的問題,正如問0除以0一樣無意義.

[594210]

這跟６÷２（１＋２）的題目一樣，明明就是１，居然可以算到９，

要把括弧前面的數字帶到括弧裡面，最基本的常識，

怎麼一堆人不知道！

[s7916380]

@594210

另外一篇有人回了

請你想起四則運算 中的 

由左到右 這項鐵則

[594210]

@s7916380 但是括弧也不能捨去，然後直接加個乘號在中間吧



[he12345698]

@594210 你幾歲阿...?

別笑死人濠嗎??

[piscoau]

其實這個題目模棱兩可,完全看個人

是出題目的人數學不好才對吧...

[MatthewCKC]

你們看看除號帶來甚麼結果?所以一般數學以避免誤會而鼓勵使用分­線多於除號.

[b0807love]

是數學家太懶惰才會這樣....

30÷2（2+3）÷5 ....幹嘛省略一個x

如果是30÷2x(2+3)÷5大家就不會算錯了吧!!!

小學老師都有說，不要偷懶算式通通都要列!!!

[pccwkw1987]

這根本就是錯誤報導 30÷2（2+3）÷5 是= 15 先乘除後加減 ()先計算=5  ()=x 所以 答覆是30÷2 x 5÷5 = 15 這到底是什麼 爛新聞

[alanlo1987]

垃圾報導。。。浪費我15分鐘 ， 2（2+3） 要先計算！ 等於10 ，然後再執行 重左到右算法。

30÷2（2+3）÷5 不等於 30÷2 x（2+3）÷5 .

[steven960929]

我"師父"要放假了... ...

[teenchankak666]

一加一等於幾啊? 2? 錯了,是11

一加一等於幾啊?11?錯了,是2

[qwe60231051]

看來只有中國的垃圾都不如的計算機才會計到 0.6

我現在中學用的

CASIO

fx-50FH

SUPER-FX PLUS H.K.E.A.A.APPROVED

也才是200多元

[mgpigpigpig]

@qwe60231051

港幣 台幣 會不會分

[vincichicken]

@qwe60231051 片中2部也是casio 只是型號不同 那你的計算機應該都是"中國的垃圾都不如的計算機"

[qwe60231051]

@vincichicken 你沒看到我打了 H.K.E.A.A. APPROVED 嗎? 它們沒有

[89574947]

用Google計算機都算對了

[koongws]

全是 乘除算法 就 先看 最前方 开始算起

= 15 （5）÷ 5

= 75 ÷ 5

= 15

[csjoecho]

出答案 是 15 的那部計算機 把它拋棄吧，有 BUG

[GasaiYuno39]

Ans的確是9

但那算式很有問題

正常算式下2(2+3)一定係最頭

如果不是都只會有加減數在前面

加上...上了中學就不會用÷ 只用-1次方，分數

[anemone1924]

30÷2（2+3）÷5

＝15*5÷5

=15

30÷ [2（2+3）]÷5

＝30÷10÷5

=3÷5

=0.6

[Savior626]

30÷2（2+3）÷5

15 (5) ÷5

75 ÷5

= 15

[justforseeeeee]

=0.6是因為計算機把÷2(2+3)當成是+2(2+3)

÷2變成+2

不錯才怪

[YipTF]

@justforseeeeee 小弟不才.. 30+2（2+3）÷5 如何算到 0.6?

[leongerqwe]

是人的按法错好不= ="

[wwd216]

其實錯是錯在人太懶了愛省略= =

打在計算機有打出x不就好了?

[717hoho]

15 lor



[NANZONET]

30/2(2+3)/5=30/10/5=3/5=0.6

[hkokppp123]

我想講香港差唔多每個中學生都有一部...

[celiceting]

專家.......害死人

[a65373385]

我fx-50FH,算出是15...

[eric800703]

那是記者沒設定模式阿，是不會用而不是機器問題好嗎?

fx-991ES一台也才五百多，八百也太誇張了吧!



[firestolen]

In practice we will always use fraction instead of division sign....

[qwe60231051]

用 CASIO Fx-50FH SUOER-FX PLUS 把 太陽能

200$-350$ 左右

[hin26022602]

我細路 小4也很快做了15-_-

[beyondthisall]

why was this video recommended to me?

[TheWildroofarms]

那和計算機沒關係......不要自己不會用就怪到機器身上..­....

[LscAndrew]

唉也, 真係聰明呀, 給你發現了這個秘密. 設計的人這樣寫是要方便用家, 不是給你研究數學. 程式設計師不是白領人工的.

[blazedraco29]

maths is alrdy so complicated and difficult, why make it worse by giving a trick question??

[op3l]

我太愛台灣新聞了，沒事想看八卦就看電視。想看真的新聞就再上g­oogle找。

[jcpersonalmugan]

fx-991es 算出來是15 我自己算也是15

[f1w78315]

寫這個數學式的人,一看就知道數學不好

[msdevnz]

好簡單= =......

[DeathHunterization]

SO EASY => (2+3) DIVIDE 5= 0

THEN, 30 divide 2=> 15 waattt what so difficult now.

[wld2005]

@DeathHunterization (2+3) divided by 5 = 0?

Are u kidding? lol

[DeathHunterization]

@wld2005 what's my comment. so long liao I forgot what I comment lol. wtfc

[DeathHunterization]

Isn't the answer 15, I hav answer like 4, when I ask my classmate.

[alex113327]

以分數形態表示

30/2(2+3)/5=30/2(2+3)/5/1

奇數項相乘 偶數項相乘化簡 30*5/2(2+3)*1=30*5/2*5*1=15

複分數轉換而已　中間項看作中括號並沒有錯

[karta0926699]

Ａ：

（30/2）X［(2+3)/5 ］  （　2(2+3)=2X(2+3)　）

（15）x （1）　Ａ：１５

＝　＝

[BoBoCookies]

條式教學上有問題 =.=

[BoBoCookies]

30/2(2+3)/5 = (30/2) x (2+3) /5 = 15,,

[chennellina]

这个已经被讨论过了，四则运算哪本教科书教过2*5可以简化成2­（5）的？这又不是代数（比方2(x+1)视为一体），没有未知­数，为什么要省去运算符号？？？一个错误的简写耍得一群人团团转­，你们输入30÷2*(2+3)÷5，保证所有计算器结果都一样­。

[Handymancinema]

30/2(2+3)/5

30/(4+6)/5

30/10/5= 0.6

30/2(2+3)/5

15(2+3)/5

75/5= 15, false brackets go first and are to be conserved as long as possible in this case. alls divions are equal.

[96169QQ]

天阿...

我算了10次還是0.6耶...

我還是回小學一年級好了~

[123yaya000]

use texas instruments!!!

[lovecveta]

不是先算括號？那還括個屁-.-？

[samewish]

we need mythbuster show to answer this mathematics

[candyxy]

try this.. 30(2+3)(10+2)(2+4).. my qn is, which term will u cal. 1st? will u cal. all that is INSIDE the 3 bracketed terms 1st, THEN sub the 30 in or will u cal. 30(2+3) 1st, followed by the other 2 bracketed terms?

For those ppl who have insisted 0.6 is the ans for 30/2(2+3)/5, and now choose to do the 3 bracketed terms 1st, I think they have just slapped their own face.. I have to stress tt BODMAS refers to terms IN the (), not OUTSIDE the () so the 2 CANNOT be a priority.. =))

[tommychuang12]

@UtubeNI The reason that the "x" sign is not used for multiplication in algebra is because it is too easily confused with the commonly used variable "x". Therefore, 5(2+3) should be treated the same as any other multiplicative function, and should not be given any special priority in the order of operations.

[tommychuang12]

@UtubeNI There is no difference between 5 x (2+3) and 5(2+3). However, there is a major difference between 5(x+1) and (5(x+1)). I am not denoting the brackets as a multiplication sign. I am saying that when two terms are placed next to each other, the function is assumed to be multiplicative. For example, ab is the same as a x b.

[123abc97]

我認為整題的重點是

2(2+3) 還是 2*(2+3)

如是左邊,那30÷2(5)÷5=0.6

如是右邊,那30÷2*(5)÷5=15

看來省略乖號的方面有問題出現

[s0910210]

P.S.

The word "unit" I just wrote means "term"

剛剛寫的"單元"一詞指的是多項式的"項"

By the way, if omitting the "×" is for replacing by students, what the hell is the meaning?

補充一點, 如果寫了乘號又省略只是為了讓學生再還原, 有什麼意義呢? 一般人會這樣省略嗎?

[s0910210]

P.S.

省略乘號其實必須加上中括號.

To omit before [] are added.

∵ 2×(2+3) = [2(2+3)]

∴ 30÷2(2+3)÷5 = 30÷[2(2+3)]÷5 ≠30÷2×(2+3)÷5

[s0910210]

Let's not talk about the question first. Just watch these 2 examples:

30÷2x Should it be 15÷x or 15x?

30÷2½ Should it be 12 or 15+½?

In the above 2 cases, both 2x and 2½ are a unit, its value must be solved first before the multiply notations. So, 2(2+3) must be a unit and you must should solve it first. The answer is 0.6.

我們先別討論這題目, 先看看這2個例子:

30÷2x 等於 15÷x 還是 15x?

30÷2½ 等於 12 還是 15+½?

在上面2題中, 2x 和 2½ 都是一個單元, 必須先被計算. 所以, 2(2+3) 也應該被當作一個單元, 你必須先算它. 答案是 0.6

[thomaswhy1014]

@s0910210 30除2X 是無解  30除2.5就是有解

但是做過練習就知道 2(2+3) 是 2 X 5 所以將題目轉換便成為30 ÷ 2 X 5 ÷ 5 = 15

[s0910210]

@thomaswhy1014

連你自己也說2(2+3)=10?

以多項式角度來看 這就是一個項啊

[AngleCritical]

if in sc they shud type 30/(2(2+3))/5 not 30/2(2+3)/5

[crosshunterx]

30÷2(2+3)÷5

=30÷2(5)÷5

now, as far as i know, solving an equation should go from left to right

and any number beside the bracket actually meant multiply

in this case, 2(5) is apparently 2x5

therefore, we can see it as

30÷2x5÷5

=15x5÷5

=75÷5

=15

[beabetter]

30÷2（2+3）÷5

= 30 X 1/ 2(2+3) X 1/5

= 0.6

不可以把2（2+3）÷5 直接÷，因为 在这里2(2+3)是1/2(2+3)

[knightseifer]

@tommychuang12

*30/2x different with 30x/2

30/2x = 15/x not 15x

[tommychuang12]

@knightseifer actually, 30/2x is the same as (30/2)x, which is 15x. don't get confused by the lack of a multiplication sign between 2 and x.

[candyxy]

@tommychuang12 ?? 30/2x is the same as (30/2)x? did u write anything wrong here? or shd i check my eyesight? 30/2x = 30÷2x.. if u want to show tt the x belongs to the whole term, write (30/2)x.. if u want to show x only belongs to 2, write 30/2x..

[tommychuang12]

@candyxy it looks confusing because of the limitations on formatting in youtube comments which don't allow you to properly show numerators and denominators.

30 ÷ 2x is essentially the same as 30 ÷ 2 * x. there is no reason why you would ever give priority to the multiplication between 2 and x. PEMDAS states that you do multiplication and division from left to right, so yes, 30/2x is the same as (30/2)x. i don't know who taught you all this stuff about "belonging," because it doesn't exist.

[candyxy]

@tommychuang12 aft looking at the term again, yes i agree u are correct.. sorry for the confusion..

[fat404]

Here's my take on the subject: fat404.posterous [dot] com/48293-2-or-288

[KaoruYuine]

I think we should solve the ( ) content first, this is the rule. My opinion is their argument is very depending on how they solve the 'division'. The answer is different if we solve the question in different order.

If we solved the summation and multiplication, then solve the division from left to right:

= {30 / 10 } / 5

= 0.3 / 5

= 0.6 (logical)

If we solved the summation and multiplication, then solve the division from right to left:

= 30 / { 10 / 5 }

= 30 / 2

= 15 ( X logical)

[SpeedMath]

How can I say to everyone?

The answer is 0.6 30÷2(2+3)÷5 [先解所有括号内的运算]

=30÷2(5)÷5 [先解除所有括号，才可以解无括号的运算]

=30÷10÷5 [从左到右解答。注意：乘和除运算是归同一级；加和减运算是归同­一级的。]

=3÷5

=0.6

[androeda89]

what a noob in maths.. =.=

[s05103581]

爛計算機= =

0.6才是答案= =

[PANZER7910]

Mathematica give 15

[SunDay1738]

common~the way of writing the equation got problem obviously~!!!

how can this be reported????

not only ashame of the lecturer but also the ChinaTimes

[choyourmilk]

無聊到爆



[candyxy]

lol i cant believe ppl who insist 0.6 is the answer.. yes that is the most popular answer but the correct answer is definitely 15.. ppl alw tot we shd mutiply 2 to the () 1st is because the problems we face are alw e.g. 30 - 2(2+3) / 5, which naturally will be multiplying the 2 to () 1st.. but for this case, it is 30 / 2*(2+3) / 5 so the left to right rule must be followed..

[woRstbB]

@candyxy

in which part you see there is a " * " between 2 and the ()? if there is a * then left to right rule will be followed, but it wasnt there dear

[sivadfa]

@candyxy What you said would be true if the multilication was explicit.

[harpuiax123]

Those who got 0.6, it is nothing unusual, for those with 15, you can just commit suicide now.

[huntercommander]

@harpuiax123 Yeah, they should do it for being outnumbered by the force of idiots who still think 0.6 and their Casio calculators is right. Am I correct, sir?

[s0nGal]

guys.. here i believe the issue is about expensive calculators which are accurate in calculating simple yet basic arithmetic problems vs cheap calculators which are more dumb. it is clearly in the law of mathematical computation that brackets go first. Hence 2(2+3) is computated as a whole, after that applying the left to right rule. (with x and ÷ before + and - )

[candyxy]

@s0nGal it's not abt the difference b/w cheap and ex ones.. cheap ones just calculate but dont have the Auto Intelligence tt help u add in terms tt are missing, ex ones do.. they help u add in the missing extra bracket so tt calculators can proceed which makes ur input becomes 30/[2(2+3)]/5 as there is no such thing as 30/2(2+3)/5.. microsoft excel shows an answer of 15. Excel does not assume any input for u, tt's y it is accurate.. =)

[myezon]

assume y = 5

30/2y = x

30 = x*2y

30 = 2xy

xy = 15

x= 15/y

x = 15/5 = 3

thus the professor and the reporter both are wrong!!

[DeathGuardZz]

lol....2(2+3) is not 2*(2+3)

2(2+3) is an entire statement and must be calculate 1st before performing any other operations on it under distributive property of multiplication...

eventhough left to right rule apply and eventhought it dont have [ ] for 2(2+3), but in this case, parentheses outrank division...

Implied multiplication has a higher priority than explicit multiplication...

[skillless]

@DeathGuardZz

I agree with you that there is a difference between 2(2+3) and 2*(2+3)

What I'm more interested in, however, is whether the first calculator will yield 15 if the input was 30 / 2 * (2 + 5) / 5 instead of the original input. If the answer is 15 instead of 0.6 for the input with an additional *, then that proves that the first calculator processes the equation with your argument. This also proves that the first cal is of a higher class as it has been through one more processss.

[huntercommander]

The 0.6 comment has even become the top comment =))

Ridiculously people know how to vote instead of how to calculate.

[operatorlink]

the rule was do the terms INSIDE the bracket fist, it didnt say outside

[huntercommander]

Has the problem been solved? Or you still don't believe in your own eyes and say the other way? :P

[legolasm]

you don't see indians having this problem =P

[zisongxD]

那个便宜计算机一定是电视台有份投资的!



[Elozt]

Using algebraic method,

30 = a, 2 = b, 3 = c, 5 = d;

a÷b(b+c)÷d

= a ÷ (2b + bc) ÷ d

Replace a, b, c and d with the respective number and volia, it gives you the equation. Lesson of the day? Parenthesis, Exponents comes first in the equation, the only divide, times, minus and plus. How can anyone mess that up?

[augthenoob]

@Elozt just a correction, it's b^2 not 2b =p yeap. agree with u =p

[cywcyw]

i think it has to do with the programming of the calculator. suppose a calculator does not have a function for the brackets, and instead over-ride the bracket method using multiplication, that would explains why the ans is 15. using RPN does not allow you to have things like 2(2+3), but reads as 2*(2+3).

[ckhanh01]

30÷2（2+3）÷5 = 30 ÷ 2 x 5 ÷ 5 = ( from left to right) = 15

From video, you can see, the answer of Casio is 15 and the answer caculator Made in China is 0.6

[zueinder89]

okok, everyone just stop it, its just a case of bad notation.

[megamovie]

Lol ignorant people.

Answer this: 1÷2(2+3) = 1/2 (2+3) or 1÷10. You decide.

Then compare with 30÷2(2+3).

[augthenoob]

if the government is giving 30 dollars to 2 family of 2 adults and 3 children and then tax them 80%, each one get how much, still 15 bucks?

[mervlam]

@augthenoob - very nice analogy!

[augthenoob]

@mervlam thx =D actually, my logic is, a bracket is not used in replacement of multiplication. let say i type 30÷(2+3)2÷5 = ? what will ur ans be? it shud be still 0.6. this is becos 2(2+3) is parenthesis and shud get the same ans as 10 be it it's 2(2+3) or (2+3)2. a bracket is not used to replace multiplications. example, (2+3)(4+5) is not simply just 5*9 but rather 2(4+5) + 3(4+5) where in this case (4+5) is a factor. but using my analogy works perfectly fine =D government will never give u 15

[mervlam]

@augthenoob - in other words, Distributive Law

[randomnessjunk]

Nice hobo teacher they got!

[cupid87]

我看到这个报道,我笑了...难道整个电视台没有一个人会数学吗­???这样也能报道错?

[mervlam]

30÷2（2+3）÷5

= 30÷(4+6)÷5 (2 is a factor of the terms in the brackets)

= 30÷10÷5

= 3÷5

= 0.6

[happyloke]

@mervlam lol

= 30÷10÷5

why the answer cant be = 30÷2 = 15

[mervlam]

@happyloke - for this you have to excute the calculations from left to right. Hence 30÷10 = 3 first, then 3 ÷ 5 = 0.6. You have to apply the BODMAS precedence rule for this.

[franknguyen007]

I think the answer is 0.6. If you want the answer is 15, the math should be 30(2+3)/2/5.

[tlwa]

If it's normal multiplication, write as 2*4

If it's a factor, you'll write as 2(4)

Please don't just take ( ) and think it's a replacement for *. Gives 2 totally different meaning. ( ) is used for factors.

If it's 30 / 2 * (3+5) / 5, write it with a *. 30 / 2(3+5) / 5 != 30 / 2 * (3+5) / 5