Finally we get to the point of your confusion. The rule you are trying
to use applies to groupings: what goes on INSIDE parentheses, not
between one set and another set. Again, I implore you: go out and
actually TRY your example. Try it with a calculator, plug it into
Google as a search, or into Mathematica. The correct answer will be 17,
no matter how much you prefer your own rules. Note that Casio
calculators made before 2007 had the same error and will get the wrong
answer if the multiplication is between parentheses. It has since been
fixed.
You sent one email asking for advice on publishing a book. I am a
mathematics instructor at a community college. I am directly
responsible for choosing the books purchased by hundreds of students,
and indirectly responsible for thousands more, because publishers ask
us for our opinions.
Here is my advice: First, put your ego away. It has no place in
teaching. Check your examples thoroughly and do not go against
convention. You have nothing new to sell. Prealgebra curriculum is
fixed. It is established in thousands of course outlines approved by
countless committees, conferences and associations. The only product
you have to sell is clarity and understanding. If you are sowing
confusion instead of clarity, I will certainly not send my students
your way.
-- Rick
--- atadricourses <bodor7@yahoo.com> wrote:
> [Brian has edited this message and will not approve any messages that
> use a semicolon to represent division.]
>
> Hi
> you should be careful to make your meaning clear whenever dealing
> with
> implied multiplication (multiplication by juxtaposition rather than
> by
> an x or a dot).
> 16/2[8-3(4-2)]+1 = ?
> 16/2 [8-3(2)]+1
> 16 /2[8-6]+1
> 16 /2[2]+1 (until here you are agree, right?)
> the rule says that parentheses outrank division. so the first 2 goes
> with the second 2 , instead of going with 16.
> the expression becomes :
> 16/4 + 1
> 4 +1 = 5
> [Brian's comment: I believe Atadricourses may be correct but could
> find no such rule on the Internet. It has always been my habit to
> never take anyone's word for something unless proven. Experts are
> wrong half the time. Leaving out the multiplication sign is keeping
> me from becoming a millionaire or doing something productive. Please
> avoid such ambiguity.
> I do not believe Atadricourses' wording of the rule and logic, even
> if the result may be correct. I hope we waste no more time arguing
> about this and that Atadricourses produces a website address with the
> rule he quotes.]
>
>
> conclusion :
> 16 / 2(2) +1 =5
> and
> 16 / 2 x 2 + 1 = 17
>
>
> I give math lessons via email, fax,
>
> messenger,Skipe,phone, and believe me 90% of the
>
> members made errors when it comes to the "order of
> operations" but now , I am sure they will give the
>
> correct answer as Rolandjo.
>
> take a look at :
>
>
http://www.atadri.com/math/order/ordermultipli.jpg
> <http://www.atadri.com/math/order/ordermultipli.jpg>
>
> perhaps you'll see what I mean.
>
> My ebook about " how to excel at the order of
>
> operations" contains 100 exercises in the form of Q&A
>
> all related on how to avoid making errors while
>
> applying the order of operations.
> Bodor
> atadricourses
>
http://www.atadri.com <http://www.atadri.com/>
>
>
>
>
> --- In Math4u@yahoogroups.com, Rick <rcastrap@...> wrote:
> >
> > The rule is still left-to-right. Try it with a calculator or
> > Mathematica.
> >
> > -- Rick
> >
> > --- "Brian E. Jensen" brianejensen@... wrote:
> >
> > > I just had a thought.
> > > 16/2*a =8a by math convention.
> > > But what happens if we leave out the multiplication sign
> > > 16/2a
> > > Now maybe it's wrong, but there is a tendency in my mind to think
> of
> > > 2a as a
> > > term or entity and come up with 16/2a=8/a
> > > So maybe leaving out the multiplication sign was done on purpose
> to
> > > trick
> > > our subconscious. I'm not so sure what the correct answer is when
> a
> > > sign is
> > > omitted.
> > >
> > > Does 16/2*a equal 16/2a ?
> > > Does anyone know the rule or how to handle when the
> multiplication
> > > sign is
> > > left out?
> > >
> > > Regards,
> > > Brian
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Mario Marotti" mmar62@...
> > > To: math4u@yahoogroups.com
> > > Sent: Wednesday, December 05, 2007 2:38 PM
> > > Subject: RE: RE : Re: [Math4u] Math persons
> > >
> > >
> > >
> > >
> > > 16 / 2 [8 – 3 (4 – 2)] + 1
> > > = 16 / 2 [8 – 3 (2)] +1
> > > = 16 / 2 [8 – 6] +1
> > > = 16 / 2 [ ] + 1
> > > = 16 / 4 +1
> > > = 4 + 1
> > > = 5
> > >
> > > Hello!
> > > This is my first message in the group.
> > > I think the ambiguity occurs when a fraction is written like 16/2
> > > instead of
> > > using the horizontal ___ quotient line.
> > >
> > > Writing
> > >
> > > 16
> > > __
> > >
> > > 2
> > >
> > > instead of (16/2), you have no problem at all.
> > >
> > > Best regards
> > > Mario
> > > _________________________________________________________________
> > > Express yourself instantly with MSN Messenger! Download today
> it's
> > > FREE!
> > > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> >
>
>
>
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