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## A math problem for the wise

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Jul 5, 2019, 12:5907/05/19
Jul 5, 2019, 15:57(edited)
01/31/18
335

I would disagree with

Using PEMDAS/BODMAS/BEDMAS you have:

8÷2(1+3) =

8÷2(4) =

4(4) =

16

If we use an outdated way of dealing with this where everything on the left side of the divide sign is divided by the right side of the divide sign we have:

8÷2(1+3) =

8÷2(4) =

8÷8 =

1

This may be outdated, but is it really? I would say that it has nothing to do with everything on the left side being divided by the right, but exactly follows  BODMAS i.e. what is in the brackets takes precedence and as you mentioned earlier the brackets are an implied multiplication.

I ought to have said "if ONE drops the brackets" rather than "if YOU drop the brackets" .The dropping of brackets idea came from a video

I watched.

For everyone who cited BODMAS or its equivalent and arrived at

8÷2(1+3) =

8÷2(4) =

Those that converted the brackets to a simple multiplication and followed the Left to Right rule must come up with the answer 16,

but is this interpretation a newer convention of the power of the brackets, or have they like politicians answered the question they wanted to answer, rather than the question they were asked?

Those that have retained the power of the brackets over both the division and left to right rule, must come up with the answer 1.

uses PEMDAS and a somewhat different convention where  multiply comes before division in the acronym but are equivalent but obey the left to right rule.  The question asked  is    4 to the power 2-2 x( 8 ÷2) + 6 .

Notice the x sign before the brackets, which she drops after completing 8÷2, they are no longer needed because the required operation is clear, perhaps this is the new convention and brackets no longer mean retain the brackets and follow PEMDAS

Using her system of PEMDAS would seem to  solve easily(?) your 2-4÷6+7 x 5+3÷17 x 5-3÷6÷12+3 = easily(?),

2-(4÷6)+(7 x 5)+[(3÷17) x{ 5-<(3÷6)÷12>}]+3 =

2-(24)+(35)+[0.18 x{ 5-<(0.5)÷12>}]+3 =

2-(24)+(35)+[0.18 x{ 5-0,42}]+3 =

2-24+35+[0.18 x 4.58]+3 =

2-24+35+0.82+3 =16.82 hopefully.

On further research on the problem.

It would seem that the BODMAS  convention has been changed, and brackets are no longer required after completing the operation inside,

After dropping the brackets,you no longer have an operand to connect the rest of the equation, so I repeat that as originally written, the problem is unsolvable.

The only way round this is that after completing the contents, the brackets are an implied simple multiplication.or the addition of another operand is required to clarify what to do with the contents of the brackets.The modern answer would seem to be 16, and the older answer 1.

Jul 5, 2019, 15:0207/05/19
Jul 6, 2019, 05:40(edited)
04/07/17
1344

KROW said:

If we use an outdated way of dealing with this where everything on the left side of the divide sign is divided by the right side of the divide sign we have:

8÷2(1+3) =

8÷2(4) =

8÷8 =

1

This may be outdated, but is it really? I would say that it has nothing to do with everything on the left side being divided by the right, but exactly follows  BODMAS i.e. what is in the brackets takes precedence and as you mentioned earlier the brackets are an implied multiplication.

I didn't say dealing with this with the equation solved as is listed above was outdated I said that doing it for the reasons to have everything on the left side of the division symbol divided by what was on the right side of the division symbol was outdated.

This equation is valid if one is doing it because an implied multiplication takes precedence over an explicit multiplication or division ... NOT BECAUSE brackets takes precedence ... what is in the brackets does take precedence but the 2 is not "in the brackets" ... and everyone who tried to do it this way wanted to put the reason forward as it is because the brackets take precedence.  But that is not what is going on ... it would be because an implied multiplication takes precedence over an explicit multiplication or division and nobody put forward that reason. It is one of the ways that this equation is done by certain professions ...

And not surprising that you would disagree with 16 being a possibility... :) ... even though numerous calculators will solve it with a 16 ... so ... so ... how about ...

Jul 5, 2019, 15:0507/05/19
04/07/17
1344

Let us suppose the OP put forward same equation and asked ... what are possible solutions for this "equation" using reasoning that is used by those that need to solve these type of equations for their profession.

1) 1

2) 16

3) 1 and 16

4) Neither 1 or 16

Jul 5, 2019, 16:1807/05/19
Jul 5, 2019, 17:39(edited)
01/31/18
335

Forgetting about the game and Fury, much to my loss,I was still figuring things out, so I think I answered your latest question on completion of my post.

I watched another video which posed the same problem with a different question 3 x 3÷3(1+2), the answers being 9 or 1.

Unfortunately the video was not in English but the end of the video, depicting a  flat earth and Galileo, left me with the impression,"Some things in this world never change, but some things do."

There are still sixty seconds in a minute,  but the second is no longer a 60th of a minute. 100 ml is no longer the same as 100 cc.

Scientists still make mistakes which is why they had to go and fix the Hubble telescope.

Returning later again, to your earlier post.

Unless your tiredness did make you a mistake,It seems I might be inconsistent with my answers to your question

A ÷ BC =? and the question, 8÷2(1+3) = ? Alice posed.

Since I didn't see "implied multiplication" in  A ÷ BC =?, I would have said A ÷ B x C using the left to right rule to give 45 and 1. Though now I am unsure if BC doesn't just mean multiply ,and wondering if technically it is implied multiplication.

The implied multiplication does give 0.05 and 1.

Unfortunately my memory cannot recall that kind of implied multiplication being included at the time I learned BODMAS.

I just recall that brackets meant multiplication, and took precedence over division.

Especially as I also recall that division had to be done first, none of this equality malarky and PEMDASLR so you can remember,

Please Excuse My Dear Aunt Sally Love Ron.

I cannot countenance that 8÷2(1+3) = 16, except as earlier, that typing the question into a browser converts the question to 8/2(1+3 )and gives the answer as 16,and to get the answer 1, you are obliged to write 8÷(2(1+3))= instead.

Jul 6, 2019, 05:2407/06/19
Jul 6, 2019, 05:54(edited)
04/07/17
1344

Besides this new post of yours I see you added a lot to your post before that one ... so I am going to deal with both of those.

An "implied/implicit multiplication" just means that a multiplication symbol isn't there but it is understood ... like 3(4+5) ... we understand is 3 x (4 + 5) or A ÷ BC we understand B and C are to be multiplied so is B x C ... explicit multiplication is where the multiplication symbol is there like 3 x 5.

There are some math teachers who also don't really understand PEMDAS/BODMAS/BEDMAS and they teach it wrong ... I watched the video and it was good ... yes there was a multiplication sign between the number and the parenthesis group  ... that is why she dropped the parenthesis when she was done ... that isn't new ... there is no need for it anymore ...  I'm over 60 years old ... it is how it has always been ...

4 to the power 2-2 x( 8 ÷2) + 6

she wrote

4 to the power 2-2 x 4 + 6

what did you want her to write this ...

4 to the power 2-2 x( 4) + 6

and if she did what difference would it make ??? ... none ... there is no longer any need for there to be a parenthesis there around the 4 anymore ... your concern about "dropped parenthesis" is a non issue ... if you have 4(1+3) it equals 4(4) = 16 here you can't just drop the parentheses unless you insert the implied multiplication sign ... also in that calculator I linked to you can put 4(4) in it and get 16 ... seems you are trying to say that not only can the OP equation NOT be solved but that 4(1+3) can't be solved ... because you have to drop the parenthesis ... that isn't what that video "taught" ... she said since they were not needed anymore ... if they are still needed you keep them or convert them to multiplication sign ...

Do notice she said in the beginning that the P has to do with what is INSIDE the parenthesis so nothing about anything outside the P ... this equation in the OP ...you wouldn't get in 5th grade or probably even higher classes ... it is purposely written to cause ambiguity and confuse ...

So back to dealing with the OP equation ... there is more than one possible answer because there are different "systems" in math to deal with such and it depends on which system you use.  In standard PEMDAS/BODMAS/BEDMAS implied multiplication DOES not take precedence over explicit multiplication or division ... however there has always been some who prefer to have implied multiplication (you can also search the terms implicit multiplication) take precedence over explicit multiplication and division.  For Physicists they often use equations where they need (a(b+c)) or they need  A ÷ (BxC)... so instead of having to write that all the time they "understand/agree" that an implied multiplication takes precedence over an explicit multiplication or division so they can have a "shorter" way to write it.  What they teach in school is not usually this modified PEMDAS/BODMAS/BEDMAS ... and that is why if you took a standard test and they had the equation in OP the answer would be 16.  Also most calculator companies have different calculators to handle the two different systems and you need to get the right calculator for what system you WANT to use.  That link I put up for YOU for a calculator I purposely put up one that uses standard PEMDAS/BODMAS/BEDMAS ... I could also put up one that uses modified PEMDAS/BODMAS/BEDMAS from the same company, but if you just typed n 4(4) you would get 16 in it also ... BECAUSE there is only the implied multiiplicaton.

So let's look at the OP equation again ...

8÷2(1+3) =

8÷2(4) =

At this point it depends on which system you use ...

If you use the standard PEMDAS/BODMAS/BEDMAS where implied multiplication DOES NOT take precedence over explicit multiplication or division (no such thing as implied division) you work left to right for divisions and multiplications (even implied multiplications)

8÷2(4) =

4(4) =

4

If you use the modified PEMDAS/BODMAS/BEDMAS where implied multiplication DOES take precedence over explicit multiplication or division (no such thing as implied division) you first work left to right with the implied multiplications then work left to write for divisions and explicit multiplications

8÷2(4) =

8÷8=

1

But it is not about the P/B (parenthesis/brackets) needing to be done first ... it is on whether implicit multiplication takes precedence over division or explicit multiplications.  And that is why I asked you about

A ÷ BC =

Where A = 3 , B = 2, C = 30 ...

Also concerning my equation ...

2-4÷6+7x5+3÷17x5-3÷6÷12+3 =

I used that equation for the problem of those who want to have everything to the left of a divide sign be divided by what is to the right  and it would be "hard" to solve it using that system ... and yes it is not hard for those using PEMDAS/BODMAS/BEDMAS because yes it makes it easy  ... and it had no implied multiplication so there was not that "problem" ... hey but you got to do your basic math properly lol and no you didn't get the right answer ... I did it and got a different answer than you and so looked at what you did and well first thing I saw is that you said (4÷6) = 24 ...after that I didn't look for anymore errors ... seems I am not the only one needing sleep ... :)

I think we have made a lot of progress here and it is something that has been going around the internet for a long time ... and it is nice having someone who is interested in understanding what is going on to discuss this with ...

Jul 6, 2019, 06:4907/06/19
04/07/17
1344

♀ SlaveSparkz ♀ said:

8    /   2   (1+3)

First the long explanation:

Note: The parenthesis coming directly after the 2 means that the amount within the brackets is to be multiplied by 2 . There is no nothing there to separate them.  i.e. 8 / 2(1+3)  is not the same as 8 / 2 x (1+3) . If you inserted the symbol you added something that was not part of the original equation in the question. Even then there would need to be brackets around the (8/2) in order for the 2 not to be distributed over the (1+3).

Everything after the division sign in this particular equation must be dived into the 8.

From your note it seems you are assuming what you are saying you are proving ... and you use this assumption throughout your proof ... that is called circular reasoning ...

Jul 6, 2019, 16:5707/06/19
01/31/18
335

Glad you enjoyed the discourse and the video, here's another,

https://www.bing.com/videos/searchq=BODMAS&qpvt=BODMAS&view=detail&mid=C8C9EB1118DAF8D5CBABC8C9EB1118DAF8D5CBAB&&FORM=VDRVRV

unfortunately a non English version ,of 9 ÷3 (2+1).

This is the video that made me think there had been a change in procedure of BODMAS.

The long puzzle you wrote was tedious to solve (and type) and I still managed to get it wrong,even after correcting other similar mistakes I made.

Returning to 8÷2(1+3) =?.

As stated earlier, it all boils down to what you do at the 8÷2(4) = ? stage.

If you turn 2(4) into 2 x 4, and if this is not a procedural error, you are forced to the answer of 16.

By removing the brackets and substituting multiplication instead, are you not changing the question by doing so?.

This is where I am perhaps remembering incorrectly in my answer of 1.

Yes the 2 is outside the brackets, but associated with it (questionable?) and this is why I think the power of the brackets outranks the division operation.

I.E. everything associated with the brackets has to be completed first, this is how I remember it should be done.

Here's where a better memory,old school books, or the teacher responsible would come in useful.

Presumably all the others who arrive at the answer 1, including the guy above, who shot down your post ,would seem to agree with me.

If you want an undisputed answer, its a bad question,impossible to answer definitively,but for other reasons than the one I gave earlier.

However it's a good question for debate.

Jul 6, 2019, 17:3107/06/19
Jul 6, 2019, 17:46(edited)
04/07/17
1344

The english video you posted specifically said what was INSIDE the parenthesis should be done first ... and this link you just posted to a new video says it can't be found  ...

"As stated earlier, it all boils down to what you do at the 8÷2(4) = ? stage."  Yup ... I think everyone agrees with that this is what it boils down to ...

"By removing the brackets and substituting multiplication instead, are you not changing the question by doing so?." ... I don't recall doing this ... just for reminder ... this is what I did ... :)

Using PEMDAS/BODMAS/BEDMAS you have:

8÷2(1+3) =

8÷2(4) =

4(4) =

16

"Presumably all the others who arrive at the answer 1, including the guy above, who shot down your post ,would seem to agree with me."

Nobody but you has posted since I started posting in this thread ... so no one has "shot down" my post(s) except you ... and my last post "tempted"  someone to engage ... :) ... who I think you are referring to as "the guy above" ...

Jul 7, 2019, 15:5107/07/19
01/31/18
335

Apologies,

I used "you" again instead of "one".

The video was there, so either it wont link, or it was " lost in translation"

I hadnt meant to shoot you down in flames, the expression arose because I misread a post, by only reading the text, I stumbled into someone criticizing your analysis, when it fact it was the reverse.

Jul 12, 2019, 08:0507/12/19
03/01/19
16

A finger down icon is needed!

Is this a place for silly questions? Whats more it is commented as "for the wise". I am sick!

Jul 23, 2019, 22:0307/23/19
07/11/19
3
16 of course.....PRMDAS  - divide before we add than mulitple......
Jul 24, 2019, 01:4707/24/19
02/21/18
1162
PRMDAS , thats a new one on me.
Jul 24, 2019, 02:0607/24/19
05/07/18
1

The answer is 1. You figure out the stuff in () first then you multiply it by 2 which squalls 8. 8÷8=1. Any number divided by itself equalls 1

Jul 24, 2019, 05:2507/24/19
02/28/19
4

The answer is 1 and 16 as it is written wrong, making it a matter of interpretation

Jul 24, 2019, 13:1307/24/19
07/14/19
4

8/2(1+3)

=8/2*(4)     First you solve whatever is in the brackets. This is following the bodmas or bidmas method i am taught in school.

=4*4           Then because there is no index number we move on to the d which is division.

=16             Finally we multiply the two numbers that remain to get our final answer.

With that i conclude that the answer is 16.
Jul 25, 2019, 02:2707/25/19
01/19/19
2

8 divided by 2 = 4

(1+3) = 4

4(4) = 16
Jul 25, 2019, 16:2207/25/19
07/12/19
1
3+1 is 4 x 8/4 _ 16
Aug 4, 2019, 15:2608/04/19
Aug 4, 2019, 16:19(edited)
02/21/18
1162

There are several versions of this mathematical conundrum to be found on the internet, this one is slightly different, has it just been regurgitated,or was this the one that started the whole thing?

Effectively they are saying it is ambigously written,but was this ambiguity never the case,or arose as a result of changes in the way things are taught and wriiten now,ignorance of original meanings and ways of doing things?

If something is unique,theres only one of them.

You cant have give more effort than 100%

I like this language version of the same idea, taken from the article linked above.

"This is like a maths version of the sentence 'He fed her cat food'.

Does it mean the man gave some food to a cat? Or he fed some cat food to a woman?

"It's impossible to tell from the information we've been given."

The article says it would be clear but an obelus is missing, so I looked that up seems in mathematics that the ÷is an obelus,and there clearly is one of those, so I am not sure what she meant.

Further wiki says this

#A  "Historically, the obelus has also been used to represent subtraction in Northern Europe; such usage continued in some parts of Europe (including Norway and, until fairly recently, Denmark).[5] In Italy, and Russia the obelus is sometimes used to denote a range of values, in engineering context.

#B The ISO 80000-2 standard for mathematical notation recommends only the solidus or fraction bar for division, or the colon for ratios; it says that the obelus "should not be used" for division.

So  with reference to part #A , some in those countries ,where 8÷2(1+3) = ? becomes 8 - 2(1+3)  =? might get even more answers  to the puzzle like 0 or 24.

with reference to part #B , the puzzle should not even contain ÷

Aug 6, 2019, 16:1408/06/19
05/27/19
1

8 divided by 8 = 1