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Author Topic: a maths question  (Read 8393 times)

hopeitfloats

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a maths question
« on: May 24, 2011, 10:11:48 am »

what does 10 + 10 x 0 = . on another message board there were 2 likely answers. 10 or 0. any thoughts. 
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nick_75au

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Re: a maths question
« Reply #1 on: May 24, 2011, 10:24:46 am »

BODMAS

http://www.mathsisfun.com/operation-order-bodmas.html

in which case the answer is 10

Nick
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sweeper

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Re: a maths question
« Reply #2 on: May 24, 2011, 10:27:20 am »

Try the concept:
ANY number multiplied by zero equals ZERO
Regards.
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hopeitfloats

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Re: a maths question
« Reply #3 on: May 24, 2011, 10:28:48 am »

thats how i was taught to but apparently the answer is 10 . maths has obviously changed since the 60's/70's.
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6705russell

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Re: a maths question
« Reply #4 on: May 24, 2011, 10:32:55 am »

thats how i was taught to but apparently the answer is 10 . maths has obviously changed since the 60's/70's.

How do you get to that?
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tigertiger

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Re: a maths question
« Reply #5 on: May 24, 2011, 10:36:38 am »

Is it (10 + 10) x 0 = 0
or is it 10 + (10 x 0) = 10

Before the days of parentheses there were rules about what operator was used first. I think the rules may still apply to computers and some calculators.
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sweeper

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Re: a maths question
« Reply #6 on: May 24, 2011, 10:40:05 am »

A form of maths illusion?
Written out as it should be considered it would be:
10 + (10x0) which would be 10 + 0 = 10

Most people ( :o) have read this "as is" : 10+ 10x0 = 20x0 = 0

DOH (to myself)
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tjones27

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Re: a maths question
« Reply #7 on: May 24, 2011, 10:40:43 am »

As the question is written 10 + 10 x 0 then it should be 0.
If the answer is 10 then its a badly written question!
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tigertiger

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Re: a maths question
« Reply #8 on: May 24, 2011, 10:48:39 am »

As the question is written 10 + 10 x 0 then it should be 0.
If the answer is 10 then its a badly written question!

If you work from left to right and do each piece as you go, then yes.

But I think there are a hierarchies of operators. Like x out trumps /, / out trumps +, and + out trumps -. (not sure of the exact order BTW)
In this case you would do the multiplication bits first, then the plus bits.
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hopeitfloats

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Re: a maths question
« Reply #9 on: May 24, 2011, 10:50:53 am »

thats the answer i was given. multiplication first then addition. parenthesis means nothing nowdays.
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tigertiger

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Re: a maths question
« Reply #10 on: May 24, 2011, 10:52:27 am »

Copied from the link. Important words below "long ago'
And even now bracketrs first.

"Operations" mean things like add, subtract, multiply, divide, squaring, etc. If it isn't a number it is probably an operation.

But, when you see something like...

7 + (6 52 + 3)

... what part should you calculate first?

Start at the left and go to the right?
Or go from right to left?

Calculate them in the wrong order, and you will get a wrong answer !

So, long ago people agreed to follow rules when doing calculations, and they are:

Order of Operations
Do things in Brackets First. Example:

       6 (5 + 3)   =   6 8   =   
48
 
       6 (5 + 3)   =   30 + 3   =   
33
(wrong)
Exponents (Powers, Roots) before Multiply, Divide, Add or Subtract. Example:

       5 22   =   5 4   =   
20
 
       5 22   =   102   =   
100
(wrong)
Multiply or Divide before you Add or Subtract. Example:

       2 + 5 3   =   2 + 15   =   
17
 
       2 + 5 3   =   7 3   =   
21
(wrong)
Otherwise just go left to right. Example:

       30 5 3   =   6 3   =   
18
 
       30 5 3   =   30 15   =   
2
(wrong)
How Do I Remember It All ... ? BODMAS !
 
B
Brackets first
O
Orders (ie Powers and Square Roots, etc.)
DM
Division and Multiplication (left-to-right)
AS
Addition and Subtraction (left-to-right)

Divide and Multiply rank equally (and go left to right).

Add and Subtract rank equally (and go left to right)



 
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dougal99

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Re: a maths question
« Reply #11 on: May 24, 2011, 10:59:39 am »

Tiger Tiger is correct about the calculation sequence in computers, without parenthesis (or brackets as I was taught) a computer will use, left to right, multiplication and division then addition and subtraction. With brackets, the rule is inside the brackets first, again left to right. Brackets within brackets, then the order is inside out.

In the absence of brackets I would use the left to right rule, as does my calculator.


However, I was also taught :

There is no such thing as a bad answer only a bad question. (Not to sure about that though)
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Glenedge

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Re: a maths question
« Reply #12 on: May 24, 2011, 11:00:00 am »

Interesting
Where do you go with ; root 3 E I cos Theter???? Sorry computer doesnt have correct symbols.  :-)

Glen
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Peewee

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Re: a maths question
« Reply #13 on: May 24, 2011, 11:36:49 am »

we use http://www.wolframalpha.com/ where i work for definitive answers  which comes out at 10.  as others have said its the way its written
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dougal99

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Re: a maths question
« Reply #14 on: May 24, 2011, 12:17:05 pm »

Intrigued by this I have just consulted my son, whose education was far more recent than mine (he's 23). He was taught brackets first, then multiplication and division, then addition and subtraction. That is how a computer does it. However, when I teach the over 50s to use computers I always point out the order of calculation they use and have never met anyone who has not expressed surprise. Another subtle change to bite you in the rear end when you're not looking.   >>:-(
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nhp651

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Re: a maths question
« Reply #15 on: May 24, 2011, 12:43:55 pm »

just done a course on this to help my daughters at school. and it is a case of BIDMAS or BODMAS THEORY that takes over riding mechanical maths, and all to do with the way modern scientific calculators are programmed.
the answer is................ 10.
10 +(  10 divided by 0 )
multiplication takes preference over division which takes preference over subtraction then addition, and scientific calculaters calculate the answer in that order. tyhat is, unless you insert your  [ ] ,( ) which then changes the order of calculation

neil.
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essex2visuvesi

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Re: a maths question
« Reply #16 on: May 24, 2011, 12:56:41 pm »

My head hurts  :o
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dougal99

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Re: a maths question
« Reply #17 on: May 24, 2011, 01:10:14 pm »

multiplication takes preference over division which takes preference over subtraction then addition, and scientific calculaters calculate the answer in that order. tyhat is, unless you insert your  [ ] ,( ) which then changes the order of calculation

neil.
Are you sure? That's not what computers do. They take Division and Multiplication first but in the order they are met left to right, then the same with addition and subtraction. So

10/4*5 = 12.5 not 0.5

Going to have a long lie down now
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nhp651

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Re: a maths question
« Reply #18 on: May 24, 2011, 01:37:24 pm »

Are you sure? That's not what computers do. They take Division and Multiplication first but in the order they are met left to right, then the same with addition and subtraction. So

10/4*5 = 12.5 not 0.5

Going to have a long lie down now

NO!, Dougal, not sure at all.......and in fact had a discussion with the lecturer about it that took up almost a full session......but that's what she insisted was correct...........so, who am i but to do and die. lol................i'm no more sure than you are, and that's what i find confusing....that an electronic device can change and dictate all mathematical process that i as a kid, and for years taught to other kids, just because some boffin has decree'd that it should be............i'll stick to my simultaneous equations, thank you, lol %% %% %% %% %% %%
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dougal99

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Re: a maths question
« Reply #19 on: May 24, 2011, 02:10:20 pm »

nhp651

whilst its a mild irritation to me not so for you. I would want it absolutely clarified for my child. Exams, like it or not, are getting more and more important in deciding where our child's future may lie. The website in one of the earlier posts, agrees with my interpretation, whilst that's not conclusive it does raise doubt over your tutor's interpretation. Have you got some examples with answers or can you get some?

Good luck
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tigertiger

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Re: a maths question
« Reply #20 on: May 24, 2011, 02:24:09 pm »

It is perhaps worth pointing out here, that we are taught by the rule of diminishing errors.

What you teach primary school kids is not as precise as what we teach middle school kids. When we get to high school we learn that some of the things taught in primary school were perhaps inaccurate to the point of being flawed. But how do you teach a child some higher level knowledge without teaching them some basics that they can comprehend.

When we go to university you discover how little we are actually taught at high school and we learn to challenge accepted 'knowledge', that we had once accepted as absolute.

The maths I use is technically flawed, but it meets my needs. However, if I was studying computer science at a higher level, what I know will not meet all cases.

And so we have the dilemma about what do we teach.

An example of the rule of diminishing errors.
I was initially taught that the basic building block of the universe (the smallest thing) was an atom.
I was latter taught that in fact the atom is made up of electrons, protons, and neutrons. I was also taught that in most cases we don't get single atoms, but molecules.
I was then taught about sub-atomic particles.

For my life I don't need to think at the micro level, but at the macro level.
For example, if I don't clean my boat off after it has been in the sea, bits go rusty, or corrode and my boat won't work.
Or if I leave things in the sun they can degrade due to UV light.
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tigertiger

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Re: a maths question
« Reply #21 on: May 24, 2011, 02:27:23 pm »

Quick point on exams.

If the syllabus says that the moon is made of cheese. Then that is what you need to write in the exam if they ask "What is the moon made of?"

We are tested on the syllabus up to high-school level.
In science we are not tested on our knowledge of science, but on our knowledge of the science syllabus we were taught. Same for all subjects.

And as such you can relax Dougal. The website you posted was for primary and secondary school maths.
What nhp651 was describing was (if I am right) tertiary level maths. Something your child will not have to worry about for a while yet.
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Nige52

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Re: a maths question
« Reply #22 on: May 24, 2011, 02:43:01 pm »

Picked up desk calculator, keyed in the sum EXACTLY as quoted in the first post, the answer is 0.
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Kleban

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Re: a maths question
« Reply #23 on: May 24, 2011, 03:17:41 pm »

From what I was taught, the sequence to calculate numeracy is:

Brackets or Divide, Multiply, Add and Subtract (BODMAS)

therefore,
10 + 10 x 0
10 + (10 x 0)
10 + 0
10



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Nige52

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Re: a maths question
« Reply #24 on: May 24, 2011, 03:20:42 pm »

There are no brackets (--) in the original question though?
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