# Simple Math



## Russianwolf (Sep 9, 2012)

Okay simple math question for you guys.

Try not to look at the answers from others before posting.

4*4+4*4+4-4*4=X

What is X?


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## seamus7227 (Sep 9, 2012)

320


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## jasontg99 (Sep 9, 2012)

I got 512.


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## Ed McDonnell (Sep 9, 2012)

320 left to right.

20 if multiplication takes precedence.

Ed


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## RDH79 (Sep 9, 2012)

In my head 320


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## hewunch (Sep 9, 2012)

20? Btw, not nice making the answer shorter than the # of min Characters


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## Ed McDonnell (Sep 9, 2012)

hewunch said:


> 20? Btw, not nice making the answer shorter than the # of min Characters



Do the multiplication first so you get

16+16+4-16=20

Ed


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## TellicoTurning (Sep 9, 2012)

Russianwolf said:


> Okay simple math question for you guys.
> 
> Try not to look at the answers from others before posting.
> 
> ...



zero


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## Wood Butcher (Sep 9, 2012)

240
WB


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## Robert Sherlock (Sep 9, 2012)

PEMDAS

4 x 4 + 4 x 4 + 4 - 4 x 4 = X
16 + 16 + 4 - 16
32 + 4 - 16
36 - 16
20


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## mredburn (Sep 9, 2012)

"Mathematicians have devised a standard order of operations for calculations involving more than one arithmetic operation.
Rule 1:  	First perform any calculations inside parentheses.
Rule 2:  	Next perform all multiplications and divisions, working from left to right.
Rule 3:  	Lastly, perform all additions and subtractions, working from left to right."

source is math goodies.com


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## JimBlack (Sep 9, 2012)

Took 5 seconds   = 20

Next?


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## Timbo (Sep 9, 2012)

x=20


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## hunter-27 (Sep 9, 2012)

20


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## cwolfs69 (Sep 9, 2012)

the answer is 
20

simple math


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## KenV (Sep 9, 2012)

My Dear Aunt Sally was the neumonic taught in grade school.

To get the 20


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## alamocdc (Sep 9, 2012)

Yep, no brainer, x = 20.


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## 76winger (Sep 9, 2012)

I got 320 initially going left to right. 

Seeing the rules, I now see the answer of 20 as well. 

I knew rule #1 & 3, but didn't know #2


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## Buzzzz4 (Sep 9, 2012)

yep, 20


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## toolcrazy (Sep 9, 2012)

Russianwolf said:


> Okay simple math question for you guys.
> 
> Try not to look at the answers from others before posting.
> 
> ...



Opps, miss a 4. Nevermind


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## Jim Burr (Sep 9, 2012)

Order of operations = 20. Sucks since I had to take algebra 3 time to get out of college!! Really...I did.


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## PenMan1 (Sep 9, 2012)

My dear Aunt Sarah says x=20

Multiply Divide Add Suhtract.


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## mredburn (Sep 9, 2012)

My dear aunt Sarah died before she could tell me the answer.:biggrin:


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## RetiredJake (Sep 9, 2012)

Robert Sherlock said:


> PEMDAS
> 
> 4 x 4 + 4 x 4 + 4 - 4 x 4 = X
> 16 + 16 + 4 - 16
> ...


 
What he said.


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## StephenM (Sep 9, 2012)

The letter right between W and Y


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## alinc100 (Sep 9, 2012)

Everyone Pities My Dear Aunt Sally

Exponents,Parenthesis,Multiplication,Division,Addition,Subtraction


X=20


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## LagniappeRob (Sep 9, 2012)

alinc100 said:


> Everyone Pities My Dear Aunt Sally
> 
> Exponents,Parenthesis,Multiplication,Division,Addition,Subtraction
> 
> ...



Not quite

Please Excuse My Dear Aunt Sally.

Parenthesis take precedence over exponents


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## Joe S. (Sep 9, 2012)

I got 20, now to read the other comments.


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## Joe S. (Sep 9, 2012)

*fistpump*


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## Joe S. (Sep 9, 2012)

1.)
cotθ cosθ / cscθ = X
2.)
41! / 38! 3! = X
3.)
 1/x=v(1/y+1/z) (solve for x)

I DARE YOU!!!


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## ctubbs (Sep 9, 2012)

16
Charles


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## MarkHix (Sep 9, 2012)

I got 20.  My dear aunt sally had a "please" for Primes.


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## tim self (Sep 9, 2012)

20.  Easy enough to do in my head.


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## Andrew_K99 (Sep 9, 2012)

20 following the order of operators.

In Canada we're taught it as BEDMAS (Brackets then Exponent then Division and/or Multiplication then Addition and/or Subtraction).

AK


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## switch62 (Sep 9, 2012)

In Aus. I was taught BODMAS Brackets, Other, Division, Multiplication, Addition, Subtraction. So X = 20

Joe S, I DARE 

1.) X = Cos² θ

2.) X = 383760

3.) x = yz*/*v(z+y) I just realised that normally when you write/evaluate an equation like this you always work out the top and bottom and then do the division last. Exception to the rule or brackets implied?

When I was programming I used brackets in equations to make sure the equations came out right as computers use the same maths rules.

How's this, my first post and it's a maths question/answer.


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## Holz Mechaniker (Sep 9, 2012)

*Please Excuse My Dear Aunt Sally*

If I properly recalled my High School algebra.
I got 16


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## dtswebb (Sep 9, 2012)

I come up with 32.

Matthew


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## Crashmph (Sep 9, 2012)

20 for the win


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## dexter0606 (Sep 10, 2012)

Russianwolf said:


> Okay simple math question for you guys.
> 
> Try not to look at the answers from others before posting.
> 
> ...


 
X=20


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## edicehouse (Sep 10, 2012)

I have seen several of these math problems being posted on FB.  Generally all order of operations.


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## PenMan1 (Sep 10, 2012)

LagniappeRob said:


> alinc100 said:
> 
> 
> > Everyone Pities My Dear Aunt Sally
> ...



If your Aunt had been named Sarah, instead of Sally no one would have to "pity or excuse Sarah......now, Sally on the other hand, could be a real P.E.M.D.A.S., LOL!

We had a teacher in school named Sally. She went nuts in the middle of the school year. The math teacher changed the mnemonic to Sarah


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## GaryMGg (Sep 10, 2012)

I can still do some math in my head! :biggrin:

20

* and / get precedence over + and - (barring parens).


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## CabinetMaker (Sep 10, 2012)

Russianwolf said:


> Okay simple math question for you guys.
> 
> Try not to look at the answers from others before posting.
> 
> ...


X=20


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## Russianwolf (Sep 10, 2012)

edicehouse said:


> I have seen several of these math problems being posted on FB.  Generally all order of operations.



amazing how many people have forgotten the simple stuff ain't it.

Yep, the answer is 20.


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## triw51 (Sep 10, 2012)

320


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## Mason Kuettel (Sep 10, 2012)

20-will be teaching that on Monday!


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## jking (Sep 10, 2012)

20 ...


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## jking (Sep 10, 2012)

Russianwolf said:


> edicehouse said:
> 
> 
> > I have seen several of these math problems being posted on FB.  Generally all order of operations.
> ...



Unfortunately, so have some of the teachers.  A friend of mine got in trouble with his son's teacher over order of operations.  The teacher wasn't teaching the kids order of operations and one of their homework problems had mixed operations in it.  When his son told him he didn't understand how of solve the problem, my friend looked at it and explained the order of operations.  Son comes home from school the next day and tells his dad he was wrong and that he failed the assignment.  My friend ended up calling to talk to the teacher and is told that isn't the way she explained it to the class and she'd appreciate it if he'd "leave the teaching to us".  He was not happy, but, didn't push it farther because he thought she'd end up punishing his son if he did.  I would have raised a major stink about it.


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## Smitty37 (Sep 10, 2012)

Russianwolf said:


> Okay simple math question for you guys.
> 
> Try not to look at the answers from others before posting.
> 
> ...


16+16+4-16=20 X=20


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## Smitty37 (Sep 10, 2012)

alinc100 said:


> Everyone Pities My Dear Aunt Sally
> 
> *Exponents,Parenthesis,Multiplication,Division,Addition,Subtraction*
> 
> ...


Nope...Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction because there can be an exponent outside the parenthesis that acts on the result of the operation within the parenthesis. i.e. (2a + 3a)Exp.2


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## Smitty37 (Sep 10, 2012)

jking said:


> Russianwolf said:
> 
> 
> > edicehouse said:
> ...


 She probably has an old "Reverse Polish Notation" calculator that performs each function as it is entered - hence simply from left to right which would give a very different answer which would be totally incorrect.  I had this happen once with one of my kids, and when the teacher told me she had explained it differently - I told her that my kid's paper had the correct answer no matter how she had explained it. When she implied that she was the teacher - I told her that my degree was just as good as hers and that I had passed mathematics through linear differential equations and the the rules of algebra were always the same.


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## Russianwolf (Sep 10, 2012)

jking said:


> Russianwolf said:
> 
> 
> > edicehouse said:
> ...


I would have done the exact thing that my mother did when I wanted to take french III and was told that not enough students had signed up. Called the Superintendent. 

granted I had to drive between schools during lunch, but I had French III on my transcript.

I'd be having a sit down with her at the very least.


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## PenMan1 (Sep 10, 2012)

Smitty:
Funny you should mention RPN, many of the better HP calculators made today STILL have a "button" to do this.


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## Smitty37 (Sep 11, 2012)

*memory*



PenMan1 said:


> Smitty:
> Funny you should mention RPN, many of the better HP calculators made today STILL have a "button" to do this.


I still remember this because we had to rewrite a lot of problems that we wanted to do so we could get the correct order of operations...It was a pain in the toosh.


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## jking (Sep 11, 2012)

I doubt an elementary school teacher would have an RPN calculator.  I think she just didn't want to get into the order of operations, yet.  Unfortunately, all that will do is confuse the kids later when they learn they've been doing their math wrong.

RPN calculators aren't hard to use, you just have to think differently when using them.  The one I had through college & my first several years out of college allowed you to enter equations.  It also stored several previous entries so you could go back & repeat the same basic calculation with different numbers.  My current one does this too, but, it's not RPN.


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## LagniappeRob (Sep 11, 2012)

RPN isn't as entered (as in left to right). It's  Operands before Operators and involves the use of a stack.

For example to simulate the same equation (including compensating for OOO) in RPN would be:

```
Stack Pos  A   B   C  D  
4                   Stack:  4
4                   Stack:  4  4
*                   Stack:  16
4                   Stack:  4  16
4                   Stack:  4  4  16
*                   Stack:  16  16
+                   Stack:  32
4                   Stack:  4  32
+                   Stack:  36
4                   Stack:  4  36
4                   Stack:  4  4  36      
*                   Stack:  16  36
-                   Stack:   20
=
```
It would be clearer if it wasn't all 4's. I still use RPN on a lab system to this day.

There... that should help with what's going on.  Entering data puts in on the LIFO stack. Operators always work on the last 2 items on the stack, and the results become 1 item on the stack. So 4, 4,  *   = 4*4 and 16 goes onto the last place in the stack.


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## Smitty37 (Sep 11, 2012)

LagniappeRob said:


> RPN isn't as entered (as in left to right). It's Operands before Operators and involves the use of a stack.
> 
> For example to simulate the same equation (including compensating for OOO) in RPN would be:
> 
> ...


Don't you also have to hit enter between operands? My last several calculators used algebraic notation for equation entry so I don't remember too much about RPN.


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