Math

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8/2(2+2) = ?

  • 1

    Votes: 4 14.3%
  • 16

    Votes: 21 75.0%
  • x to the power of 9 billion

    Votes: 0 0.0%
  • Cookies

    Votes: 3 10.7%

  • Total voters
    28
Feb 7, 2015
22,418
413
0
#41
Does anyone have a graphing calculator? Just type in the equation and see what it comes up with.

I come up with 1.

But I understand how you could come up with 16.
A Graphing Calculator I just used gives this: (Couldn't make the underline under the 8 any longer)

8
2(2+2)

=1​
 
Last edited:

Huglife

Senior Member
Aug 15, 2016
2,543
50
48
#42
Were starting a debate on math... On a saturday
 

Huglife

Senior Member
Aug 15, 2016
2,543
50
48
#43
I just looked it up... The Internet said 16. So i was right! Yeah!
 

Angela_grace

Senior Member
Jan 3, 2016
196
10
18
#44
I have a TI 84 plus graphing calculator. It said 16
 
W

wwjd_kilden

Guest
#46
Both are right

as long as you don't have the

xxx
_____
xxx

to tell you where the numbers are

- Credits to my math crazy FB friend
 

posthuman

Senior Member
Jul 31, 2013
37,443
13,377
113
#47
most of you are treating it like it's this:

(8/2)(2+2)

so

(8/2)(4)

(4)(4)

16

but it's not. it's

8/2(2+2)

8/2(4)

8/8

1

what i get from all this is that it would save a lot of confusion if we wrote

8/(2(2+2))

or, better yet,

CodeCogsEqn.png

because the way most of you are reading it is that it should be

CodeCogsEqn (1).png

or

CodeCogsEqn (2).png

which, when i look at it, i think it shouldn't be -- that it should be 1.
the issue is that multiplication & division are in a way the same operation and take the same precedent. do those types of operations from right to left in the equation and you should be fine, most of the time -- or best thing, like i said, write equations clearly so there's no confusion about what you mean.

if you just plug what is written here into software, some of it is going to give you 16, and some of it is going to give you 1. it depends on whether you assume that what follows after the "\" is all under it, or if only the first term after "\" should be. some softwares avoid this kind of mistake altogether by refusing to treat 2(2+2) as a legitimate entry: they won't assume that writing something next to a parenthesis is supposed to mean 'multiply' -- in order to force user input to be clear about what they want multiplied with what.
some software will give you an error, some will give you 1, and some will give you 16.

have we broken math???
no -- we're just illustrating how important it is to be very precise about our language.

the lesson here is that the equation is unclear and needs to be clarified. either 1 or 16 is arguable -- but i think, correctly, the answer 1 -- because (2+2) term is not multiplied by 8, it's multiplied by 2. in other words, you are following 'order of operations' thinking it is written like this:

CodeCogsEqn (2).png

but it sure looks to me like it's actually written like this:

CodeCogsEqn.png

 
Last edited:

Huglife

Senior Member
Aug 15, 2016
2,543
50
48
#48
Awww... I think you think you broke my brain...
 
Feb 7, 2015
22,418
413
0
#51
Yep, I should not have second-guessed,
.... Please Excuse My Dear Aunt Sally....
 
Last edited:

posthuman

Senior Member
Jul 31, 2013
37,443
13,377
113
#52
Here is a graphing calculator to use. Just type in the equation with their keypad, and the answer will be shown without you having to do anything.

https://www.desmos.com/calculator
hey this is a pretty nice site :)
thanks for the link, i bookmarked it.

i was using this site to type in equations --
https://www.codecogs.com/latex/eqneditor.php

it's a latex generator, which is the most commonly used format to type 'official' papers for math or science. those people frown on using microsoft word etc.
i have to write my thesis in TeX, but i didn't want to have to learn all the weird language ((it's like writing code)) so i found some things that let you just hit buttons to insert the right codelets that produce equations. i like the site i linked to because it makes very pretty equations easily, that you can save as pictures and insert in other places :)
 

Huglife

Senior Member
Aug 15, 2016
2,543
50
48
#55
So the anserwe is 16, right? Its what my calculater said... And before that i did it in my head:) that makes me feel Steven hHawking smart lol
 
W

wwjd_kilden

Guest
#56
The answer can be both 16 and 1

and as long as you just write the problem out on one line, both answers are theoretically correct, as we don't know what belongs where. It wasn't meant to be written out the way the OP displays it, which is the entire point, you WILL get two potential answers.
 

posthuman

Senior Member
Jul 31, 2013
37,443
13,377
113
#58
do those types of operations from right to left in the equation
i shouldn't have said this. it should left to right, and multiplying before dividing.
that means you do

8/2(2+2)

8/2(4)​

which is

8/2*4​

do multiplication first

8/8 = 1​

there's not "2 right answers" -- multiplication comes before division, so the answer is 1.

PEMDAS


when you type this into google,

8/2(2+2)


it will give you 16. but notice what it does -- it automatically puts parenthesis

(8/2)(2+2)


which aren't actually there.

Capture.JPG

some software assumes this, and some doesn't.
 

Angela_grace

Senior Member
Jan 3, 2016
196
10
18
#60
Multiplication and division are actually interchangeable in order of operations just as addition and subtraction are. Thus, it should be from left to right. The reason it has multiplication is because you learn it first. The whole PEDMAS thing can be confusing in that aspect.