Author Topic: What is 8 ÷ 2(2 + 2) = ?  (Read 714 times)

Offline Audio

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #15 on: October 22, 2019, 09:19 »
The question is, why do they use a bracket in the first place?

2(2+2).

You can do a 2 X 2+2  but no, you didn't do that.  Instead you purposely do a (2+2).  Tell me why do you use a bracket?  The answer is clear ....it is to separate (2+2) so that you do not end up doing a 2 X 2+2 which give you the result of 6. That is why you must attempt to calculate what's inside the bracket first; you add (2+2) first and then multiple by 2 which give you an answer of 8. 

Hence the answer to 8/2(2+2) = 1.

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Offline AndrewC

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #16 on: October 22, 2019, 09:25 »
The question is, why do they use a bracket in the first place?
...

I disagree. The point is not the bracket itself, but the implied multiplication by skipping the "x" (multiply sign).

8 / 2 x (2+2) is NOT THE SAME as 8 / 2(2+2)... Bracket is involved in both, but the former is 16, while the latter 1 because of the implied multiplication.

QED  ;D
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Offline Audio

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #17 on: October 22, 2019, 09:41 »
I disagree. The point is not the bracket itself, but the implied multiplication by skipping the "x" (multiply sign).

8 / 2 x (2+2) is NOT THE SAME as 8 / 2(2+2)... Bracket is involved in both, but the former is 16, while the latter 1 because of the implied multiplication.

QED  ;D

2 X(2+2) is not 2(2+2)??

2 X(2+2) = 8
2(2+2) = 8

??

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Offline chewed

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #18 on: October 22, 2019, 09:46 »
I disagree. The point is not the bracket itself, but the implied multiplication by skipping the "x" (multiply sign).

8 / 2 x (2+2) is NOT THE SAME as 8 / 2(2+2)... Bracket is involved in both, but the former is 16, while the latter 1 because of the implied multiplication.

QED  ;D

again, if we write it out what you said 8/2 x (2+2)  is actually   

  8
-----     x  (2+2)  = 16
  2

but for 8/2(2+2) it is

       8
-------------
   2(2+2)


i think we have to be very clear? Else it can be seriously wrong.

Offline AndrewC

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #19 on: October 22, 2019, 09:50 »
2 X(2+2) is not 2(2+2)??

2 X(2+2) = 8
2(2+2) = 8

??

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You're missing the point and looking at only a part of the whole.

In 8 / 2 x (2 + 2) .... the order of operation is bracket first, then left to right with division having a higher precedence than multiplication. Hence 8 / 2 followed by x 4. i.e. 16

In 8 / 2 (2 + 2)... the order of operation is bracket first, followed by multiplication, only then left to right with the division. Hence 2 x (4) first, followed by 8 / 8. i.e. 1

Once again, the ambiguity in this case is because BODMAS doesn't say anything about implied multiplication :)
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Offline Audio

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #20 on: October 22, 2019, 10:28 »
You're missing the point and looking at only a part of the whole.

In 8 / 2 x (2 + 2) .... the order of operation is bracket first, then left to right with division having a higher precedence than multiplication. Hence 8 / 2 followed by x 4. i.e. 16

In 8 / 2 (2 + 2)... the order of operation is bracket first, followed by multiplication, only then left to right with the division. Hence 2 x (4) first, followed by 8 / 8. i.e. 1

Once again, the ambiguity in this case is because BODMAS doesn't say anything about implied multiplication :)

If the answer was meant to be 16, then it should be

(8/2)(2+2) which it isn't.  The second bracket is missing.

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Offline AndrewC

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #21 on: October 22, 2019, 10:58 »
If the answer was meant to be 16, then it should be

(8/2)(2+2) which it isn't.  The second bracket is missing.

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It's not complicated  :P...  I'm saying the answer to the original post, as in the subject line of this thread, is 1 (not 16)... because of the implied multiplication in the full mathematical term.

The confusion some people have is because they've forgotten (or are unaware), that implied multiplication has a precedence over division (especially if they're used to using BODMAS).
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Offline Gondon72

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #22 on: October 22, 2019, 11:03 »
1

1. 2+2=4
2. 2*4= 8
3. 8/8 = 1


« Last Edit: October 22, 2019, 11:20 by Gondon72 »

Offline bean

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #23 on: October 22, 2019, 11:13 »
No it's not actually. Google "Implied Multiplication" (it has a higher precedence than division :))

I never heard of implied multiplication before so I actually google. I think "Implied multiplication" applied to thing like 1/2x, where x is an variable. In this case, we mean 1 / (2x). But it has nothing to do with bracket as in the situation like 8/2(4).

I still put my money on 8/2(4) = 16. However, I will not consciously write this kind of expression unless I want to mislead.

Offline AndrewC

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #24 on: October 22, 2019, 11:19 »
I never heard of implied multiplication before so I actually google. ...

Implied Multiplication doesn't apply to just variable, it's also applies to mathematical terms with factors against bracketed terms. Google harder (beyond just Wikipedia lah...) :)
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Offline Audio

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #25 on: October 22, 2019, 13:41 »
It is just me.  I apply BODMAS but looking at the expression, I will clear bracket first and everything under the divisor before actually dividing.   Never like loose ends.

Answer is 1.

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Online jonlee

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #26 on: October 22, 2019, 15:02 »
I old school ... so I am thought this way:

8 ÷ 2(2 + 2)

        8
= -------------
     2(2+2)

        8
= -------------
     2(4)

        8
= -------------
        8

= 1


8 ÷ 2 x (2 + 2) 
= 8 ÷ 2 x (4)
= 4 x (4)
= 16

(8/2)(2+2)
= (4)(4)
= 16

Offline AndrewC

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #27 on: October 22, 2019, 15:09 »
288 Tanks or 2 Tanks?

<a href="http://www.youtube.com/v/bwpWw-iVKHc&fs=1" target="_blank" class="new_win">http://www.youtube.com/v/bwpWw-iVKHc&fs=1</a>

ps:

A quick Google reveals that this same math problem has been making the 'net rounds over the last decade or so without a definitive answer from anyone appropriately authorative.

Interestingly, Wolfram Alpha gives both results depending on which Division operator is used;
When expressed as in this thread Subject; https://www.wolframalpha.com/input/?i=8+div+2%282%2B2%29 = 1
When expressed with the "/" operator; https://www.wolframalpha.com/input/?i=8%2F2%282%2B2%29 = 16
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Offline desray

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Re: What is 8 ÷ 2(2 + 2) = ?
« Reply #28 on: October 22, 2019, 19:21 »
Haha. I didn’t expect so many responses in this innocuous thread.


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