Another Math Problem

[pawliukazz]

Absolutely none. The problem is to produce the answer not have an answer already so why would you have reversed the problem in the first place.

Also we are talking a numerical answer not a capacity or volume answer (if it was volume it would have been stated at the start of the problem) therefore the use of that particular example is a non entity in this case.

The other point that you made is the use of () being optional...if optional why would there be a law for their usage in the first place. If optional the problem is still open to personal interpretation and therefore 2 different answers depending on your standpoint.

So in summary "because you do the sequence wrong. logically thinking" is a bad statement. Logically thinking I am right. Logically I add 3 and 4 and then multiply by 5

it's really hard to explain for me in english, but you always must think (2*2) as one number (4) which leads to 3+4*5=23, 4*5=20, 3+20=23

another one, how would you solve this one

1+1*2+1*2+1*2
and
1+(1*2)+(1*2)+(1*2)

[Stuart 0366]

I understand fine what you are trying to explain. It is the reason for it being that way that I disagree with. Can you understand my reasoning?

22
7

[SpLinter]

i agree with the science behind the maths and the answer it gives

but why dont we just right it the correct way ie,

2*2+1 simpler dont you think?

Maybe the question itself was written specifically to test or enhance the students knowledge of BOD-MAS.

If so, then given the response it was well designed and well targeted.

Quite frankly it is not always possible to place multiplication to the left of addition sometimes you just need to understand the rules.

It is widely accepted that it is best (more flexible and easier to compose and interpret) to keep language as context free (less dependent on the structure of the whole) as possible and I believe that is one of the core reasons for the convention.

To demonstrate:
Imagine having to write a paper explaining a complex argument about a fine point of logic with the simple grammatical rule that over the whole scope of the paper all instances of the word AND must appear before all instances of the word OR. If you break this fundamental rule even once then your whole paper makes no sense.
Now compare this with another simple rule where AND is more tightly binding than OR unless I override it using brackets which is basically what we have.

[pawliukazz]

I understand fine what you are trying to explain. It is the reason for it being that way that I disagree with. Can you understand my reasoning?

22
7

The answers are both the same - 7!

Well if you understand what i say, and if you are asking why multiplication must be in the first place - i have been thinking about that long time ago, and trust me, noone can help you, you just have to think it by yourself i mean if you don't understand it logically, yes logically, then noone can explain for you, it's like asking how to move your arm, you are moving it but you have no idea what your brains are doing to make your arm move, so i suggest to find a relaxing moment, and just deeply think about that i hope you understood what i wanted to say

[Stuart 0366]

The answers are both the same - 7!

Well if you understand what i say, and if you are asking why multiplication must be in the first place - i have been thinking about that long time ago, and trust me, noone can help you, you just have to think it by yourself i mean if you don't understand it logically, yes logically, then noone can explain for you, it's like asking how to move your arm, you are moving it but you have no idea what your brains are doing to make your arm move, so i suggest to find a relaxing moment, and just deeply think about that i hope you understood what i wanted to say

It is not logical to climb over the fence and then open the gate so why is it logical to complete the middle of a math problem (the multiplication in this instance) before the first part unless there are other reasons such as ()
Your concept of logic does not compute with me mate sorry

[pawliukazz]

It is not logical to climb over the fence and then open the gate so why is it logical to complete the middle of a math problem (the multiplication in this instance) before the first part unless there are other reasons such as ()
Your concept of logic does not compute with me mate sorry

There's nothing to be sorry about at all... Just know, it's hard but it's possible to lets say "logically prove" this thing about multiplication

[rabihhammoud]

How can 3+4x5=23?
My boy has been told that is the answer to this sum...he is in 3rd year at college.
My response, (as was his) is the only way this would work is if the sum is written 3+(4x5)=23
Are we right?

R u kiding? or u really have doubt!!!???
anyway: 3+4*5= 23 FOR SUREEEEEEEEE (basic math).

because the multiply sign is stronger than the addtion so we start with the stronger sign....

and for example: 8/2*2=8 so here we have divide and multiplication ( both are on the same level) so we start in the logical order (left to right)

[rabihhammoud]

I understand fine what you are trying to explain. It is the reason for it being that way that I disagree with. Can you understand my reasoning?

22
7

IN Both cases its 7

[SpLinter]

OK...

If you want to understand standard notation, why not look at a working alternative which is entirely based on left to right ordering and try to develop an understanding based on comparing the structure of each alternative?

Look up Polish Notation (and Reverse Polish) and ask yourself why it has that particular structure.

Then ask yourself if you would really want to attempt to transpose complex algebraic problems expressed in this fashion.

[skegsagypsy]

My head hurts,,,,,,,,,,,,,,,the answer to the first query logically is 35 ~~~~ all the other theory's

[Mjolinor]

My head hurts,,,,,,,,,,,,,,,the answer to the first query logically is 35 ~~~~ all the other theory's

You are correct, no need for a hurty head about it.

Sadly logic can only be applied sensibly if you know the rules that the logic is applied to. If you do not then the application of logic is not valid.

[Mjolinor]

Application of logic without knowing the rules.

Heading South on the M6, 3 lanes of stationary traffic heading South, no traffic heading North.

Why do you not crossover and drive South down the North carriageway?

Application of logic without the rule says that you should but you know the rules so you apply logic with the correct rules applied and you don't do it.

[manxspud]

[masur123]

Application of logic without knowing the rules.

Heading South on the M6, 3 lanes of stationary traffic heading South, no traffic heading North.

Why do you not crossover and drive South down the North carriageway?

Application of logic without the rule says that you should but you know the rules so you apply logic with the correct rules applied and you don't do it.

Probably the crash barrier in the middle of the road... otherwise I would!

[Canker_Canison]

Do you really want to know why this is causing so much trouble?

This is a UK problem with teaching. It starts with the infants, they learn the basics, + & -.

Then it's progressed to x & /, followed by %, square roots & powers.

But because they teach + & - first, it's always placed first on paper. This continues right through school.

As we get older we are introduced to equations & algebra. Here we are introduced to brackets, ( ). These are done first. Now some teachers will explain the full rules, but most won't as it's not required for GCSE.

By the time these kids get to A-level & Degree courses they have to be re-taught all the rules of mathematics. Just to undo what they thought was right.

It all comes down to the standards set by the government. Give everyone the basics in the easiest way. They will survive most jobs with this level of maths.
If they go further then they'll have to learn it all again, but their smart enough so it's not an issue.


This is why it's had for some to follow the problem. Because most people don't go on to do A-level Maths, Physics, etc.... they were never given all the knowledge they need to understand the problem. But even at A-level brackets are still used to make the understanding easier.