48÷2(9+3) = ?

[kender]

Originally Posted By: Quattro Pete
Originally Posted By: kender

So MyAlgebra.com is wrong huh? I guess all the math teachers I had back in the 70's were wrong too. LOL!!

Yup.

I've had a few clueless math teachers over the years, too, sadly.



This one must be wrong too, huh?
freemathhelp.com/equation-solver.php

 

[Hokiefyd]

Originally Posted By: Johnny
Well, I've come to one conclusion, six pages of disagreement means all of you would qualify to be congressmen and run the budget.

HA HA HA HA!!! Best response yet!!!

 

[ToyotaNSaturn]

Cool topic. We all got it wrong, choosing 2 rather than 288.

 

[Drew99GT]

The only remaining question I have is, will it blend?

 

[Shannow]

:doh:

eating breakfast, saw the thread title and thought "2"

 

[Quattro Pete]

Originally Posted By: kender
This one must be wrong too, huh?
freemathhelp.com/equation-solver.php

Yes. It is the same exact interface as myalgebra.com, so it uses the same faulty logic.

Google gives the right answer:
http://www.google.com/search?source=ig&a...mp;aql=&oq=

 

[FloatingBrick]

What I absolutely love about this post is how it demonstrates that something as precise as math, isn't. It really comes down to the man made rules of operations.

I came up with 288 only because Mrs. Phillips drilled the rules into my head in 4th grade.

 

[Vikas]

Originally Posted By: kender
0.05

Or maybe not. I don't know if the "/" is used the same way as the traditional division symbol. With the traditional symbol the answer is 0.05


Exactly; "one over two eX" is understood to be the reciprocal of "two eX" which is equivalent to "one divided by two and then divided by eX". This is by convention.

When using paper and pencil, the division sign is supposed to distinguish between dividend and divisor.

My other example of distributing divisor was a poor attempt of injecting little more humor in to this topic.

- Vikas

 

[kender]

Originally Posted By: Quattro Pete
Originally Posted By: kender
This one must be wrong too, huh?
freemathhelp.com/equation-solver.php

Yes. It is the same exact interface as myalgebra.com, so it uses the same faulty logic.

Google gives the right answer:
http://www.google.com/search?source=ig&a...mp;aql=&oq=


purplemath.com says....2
They say that a multiplication indicated by a number to the left of a "(" is "stronger" than a regular "x" . Therefore you would multiply 2(9+3) before you divide 48 by the result. GOOGLE is wrong.

 

[Vikas]

OK, *this* settles it

 

[morris]

man o man iam glad i flunked math

 

[wavinwayne]

288. Perhaps (48÷2)(9+3) would have been a better way to present the question?

 

[Vikas]

Originally Posted By: wavinwayne
288. Perhaps (48÷2)(9+3) would have been a better way to present the question?


Do you think we would have had 7 pages of discussion if it was presented like that?

Actually, I was surprised that Casio did come up with "2". It is using the conventional method of how students and teachers have interpreted "one over two ex" for centuries.

Calculators which started understanding that convention are somewhat newer concept. My first four function calculator had no order of precedence. It went strictly left to right, calculating as it went along. You also have to distinguish between precedence as understood by computer languages and general mathematical expressions. For example. as presented here, "C" would give you syntax error as there is no concept of the implied multiplication. The "C" language rule needs an explicit "*" before it will do the multiplication. Many of the newer compiler warns you when a programmer writes a statement which the compiler "thinks" that she did not really mean it the way compiler is going to interpret it! So even thought there are stringent rules in a computer language, some rules are counter intuitive and are prone to programming errors.

I have to hand it to OP. I skipped this first time but now I am completely sucked in to it

- Vikas
- Vikas

 

[tom slick]

My wife teaches math, she has a TI-85, I have a TI-86, and she deals with students with various models of calculators. She new exactly where the issue is between the two calculators. The TI-85 needs the problem to be input as 48/2*(9+3) for it to solve correctly, it was fixed in later models. If I were inputting it I would have added parenthesis to insure it was solved correctly; (48/2)(12)
You guys that distributed the 2 fail. P in PEMDAS means INSIDE the parenthesis, that means 9+3=12. Now the problem is 48/2*12. Using PEMDAS from left to right 48/2=24, and 24*12=288.
There's no interpretation and it shows that total reliance on technology can fail you.

 

[rshunter]

Originally Posted By: Johnny
Well, I've come to one conclusion, six pages of disagreement means all of you would qualify to be congressmen and run the budget.

I haven't seen any evidence that they don't...

 

[crinkles]

We've had physics 101.

Now math 101.

Who's gonna start the chem 101 thread?

 

[Colt45ws]

When I saw this problem I initially got 2 as well, but I had a brain [censored] and interpreted it wrong. I did 48/2/(9+3) for some reason. I got 288 once I did it correctly.

 

[Al]

Originally Posted By: Vikas
OK, *this* settles it

Don't buy a Cassio

 

[Scienceman]

 

[crinkles]

I can't see how this can go wrong when using RPN.