Mathemagicians - Help my brain fog here!

steaky360

Moderator
Moderator
Its all down to the orders of methematical operation, Wiki might be useful here https://en.wikipedia.org/wiki/Order_of_operations
But I would still argue that for it to be 16, it either needs another pair of brackets or a space and multiplication sign...
(8/2)(2+2)=16 or 8/2x(2+2)=16
But 8/2(2+2) is 8 divided by 2(2+2) which is 1

You'd need to talk to proper mathematicians to get more info I think, I only went as far as A Level.
8/2x(2+2) is not the same as (8/2)(2+2) they are different things because of the brackets. 8/2x(2+2) is the same as 8/2(2+2) which both equal 1.
 

polycrac

Rising Star
As a Maths lecturer, this one never stops giving me grief - I have a session on it for a foundation year class I give. Fundamentally, it is deliberately written poorly to provoke confusion - you can do the same with sentences, it doesn't make the writer clever or the reader dumb, it is just poor practice!
 

Scott

Behold The Ford Mondeo
Moderator
Its all down to the orders of methematical operation, Wiki might be useful here https://en.wikipedia.org/wiki/Order_of_operations
But I would still argue that for it to be 16, it either needs another pair of brackets or a space and multiplication sign...
(8/2)(2+2)=16 or 8/2x(2+2)=16
But 8/2(2+2) is 8 divided by 2(2+2) which is 1

You'd need to talk to proper mathematicians to get more info I think, I only went as far as A Level.

Order of operations is BODMAS, I just used the acronym earlier.

Definitely doesn't need brackets. Brackets would make the answer 1.

8 ÷ 2(2 + 2) is equal to 8 ÷ 2 * (2 + 2) which is equal to 8 ÷ 2 * 4 which is then calculated left to right.

To get 1, there would need to be additional brackets

8 ÷ (2(2 + 2) is equal to 8 ÷ (2 * (2 + 2) which is equal to 8 ÷ (2 * (4)) which is equal to 8 ÷ (2 * 4) which is 8 ÷ (8) which is 1.

The rule is simply calculate inside the brackets. Once this is done.... there are no brackets.


I think most of the problems with these things on facebook and whatever you see it on, it is written to confuse and in essence cause arguments, so often they are missing the relevant symbols that would make it mathematically correct notation, and therefore its very easy to read it wrong
This is exactly it. I knew this from the offset but what I wanted was categoric proof that one way is correct......it doesn't exist though as it's just an acceptance in mathematics. I'm happy enough with that though as the intention of everyone who uses it to the widely accepted method is the same.
 
D

Deleted member 17413

Guest
As a Maths lecturer, this one never stops giving me grief - I have a session on it for a foundation year class I give. Fundamentally, it is deliberately written poorly to provoke confusion - you can do the same with sentences, it doesn't make the writer clever or the reader dumb, it is just poor practice!
Yep... like I said, lazy and incomplete!

As a maths lecturer, would you mind telling us what should be going on with it?
 

Scott

Behold The Ford Mondeo
Moderator
As a Maths lecturer, this one never stops giving me grief - I have a session on it for a foundation year class I give. Fundamentally, it is deliberately written poorly to provoke confusion - you can do the same with sentences, it doesn't make the writer clever or the reader dumb, it is just poor practice!

Totally understand that. My intention with this thread was not to debate the answer to the equation. For me it's not up for debate, the answer is 16. Whether this thread leads to understanding why is an offshoot.

However, given your background...... and using the 5 why's. Can the answer be proven in a rule or is it just an accepted norm that the multiplication is inferred?

I was reading the link from @steaky360 that explained the ambiguity of the missing symbol can cause confusion in computer languages, depending how it is interpreted.

From that.... I would surmise that there isn't an actual hard and fast rule as otherwise it would have been programmed in, it's rather just an accepted standard among mathematicians and anyone surrounding mathematics in general?
 

polycrac

Rising Star
Here you go, the opening class for my foundation lot, so mostly about giving them some confidence and getting them to be clear in writing Maths.
 

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D

Deleted member 17413

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Here you go, the opening class for my foundation lot, so mostly about giving them some confidence and getting them to be clear in writing Maths.
LOL....so...i'm right on the theory, but wrong in practice!
 

polycrac

Rising Star
You're as right as anyone is. Putting things above and below a divisor makes it clear, as does adding additional brackets, but then people don't argue, so the clickbait doesn't work...
 

ojmck22

Bronze Level Poster
Ok, I saw an equation on FB that's apparently dividing the world. The world is already split... you either know how to do this stuff.... or you don't, so it's hardly a time to call Ripley's when people disagree. However, I'm disagreeing with myself now as I can't for the life of me rationalise the logic.

Here is the exact problem

8 ÷ 2(2 + 2) = ?

Now.... to me, the answer is 16... because.....

8 ÷ 2(4) = ? (Brackets first)
8 ÷ 2 * 4 = ? (Spread out)
4 * 4 = ? (Left to right)
16 - Answer

The foggy part for me, is automatically assuming that 2 of something means multiplication. Here is where my head is taking me...

8 ÷ 2(x)

Why is the above 8 ÷ 2 * x and not 8 ÷ 2x

If it were 2x, and we substitute the 4 for the x, the answer becomes 1.

Is it as grey an area as it seems where there isn't really a rule, it's just an accepted given?

I completely understand that these equations are written with that particular grey area to cause the division..... but my real question is, with the grey area in play. Does that mean that both answers are in fact potentially correct?

I've tried numerous ways to rationalise the problem. I've tried multiplying both sides of the equation by the problematic part.... but that only makes it more difficult. If 2(x) is an actual thing..... and there isn't an assumption to be made..... does that make BODMAS incomplete and in need of an additional letter being stuck in there?

Or is 2(x) simply 2*x and not 2x?

Answers on a postcard please.
the answer is 1 :)
 
D

Deleted member 17413

Guest
Oh but stuff like that is great for confusing relatives or friends who never really did much maths, I've definitely had my fun claiming that 1+1=1 :)
I used to try and pull a stunt claiming half of 10 was in fact 5.5 reoccurring... as zero isnt a number, but a consruct (or something like that.... typical 16 year old with halfbaked knowledge).
 

Martinr36

MOST VALUED CONTRIBUTOR
The middle day of the week is in fact Thursday not Wednesday, with the midpoint of the week being 12:00 noon on Thusrsday so all those that call wednesday hump day are wrong.......................
 

ubuysa

The BSOD Doctor
As a Maths lecturer, this one never stops giving me grief - I have a session on it for a foundation year class I give. Fundamentally, it is deliberately written poorly to provoke confusion - you can do the same with sentences, it doesn't make the writer clever or the reader dumb, it is just poor practice!
Quite right. We used to see the same thing with some application programmers back in the day. They'd write the most obtuse and obscure statements they could think off and then call it elegant code. They never properly documented it either!
 

Rakk

The Awesome
Moderator
Quite right. We used to see the same thing with some application programmers back in the day. They'd write the most obtuse and obscure statements they could think off and then call it elegant code. They never properly documented it either!
What do you mean 'back in the day', it still stinking happens!
 

Scott

Behold The Ford Mondeo
Moderator
The middle day of the week is in fact Thursday not Wednesday, with the midpoint of the week being 12:00 noon on Thusrsday so all those that call wednesday hump day are wrong.......................

It's down to the fact that most work Mon-Fri, with Wed being the mid-point of the working week.

I can never wait to get Wed by with as I know I'm on the home straight to the weekend :D
 
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