multiplication before addition
Apr 2, 2008 at 12:01 AM Post #2 of 39

Wodgy

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Because it's a convention to avoid fully parenthesizing expressions. Nothing more. The convention could be anything you like.

If this bugs you, get a Reverse Polish Notation (RPN) calculator and control the order of operations yourself.
 
Apr 2, 2008 at 12:04 AM Post #3 of 39

pez

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Well usually when you see a problem like this it is divided by parenthesis. I'm sure you are familar with PEMDAS or as some refer to as Please Excuse My Dear Aunt Sally. Since these are usually placed inside parenthesis, and the rule states that you do the parenthesis first, you would have to what's inside them first, which in this case is (2x2). After that is solved, the parenthesis are negated and you can then find the final solution.
 
Apr 2, 2008 at 12:09 AM Post #4 of 39

Duggeh

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PEMDAS? I was taught BODMAS (brackets, order, division, multiplication, addition, subtraction). Whats PEMDAS? (parenthesis, exponentials, multiply, divide, add, subtract)?
 
Apr 2, 2008 at 12:14 AM Post #5 of 39

Mher6

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Quote:

Originally Posted by Duggeh /img/forum/go_quote.gif
PEMDAS? I was taught BODMAS (brackets, order, division, multiplication, addition, subtraction). Whats PEMDAS? (parenthesis, exponentials, multiply, divide, add, subtract)?


Yep, that's what PEMDAS is and that's the way I was taught.
 
Apr 2, 2008 at 12:59 AM Post #9 of 39

shellylh

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Quote:

Originally Posted by Wodgy /img/forum/go_quote.gif
Because it's a convention to avoid fully parenthesizing expressions. Nothing more. The convention could be anything you like.

If this bugs you, get a Reverse Polish Notation (RPN) calculator and control the order of operations yourself.



x2, well said
 
Apr 2, 2008 at 1:04 AM Post #11 of 39

Arainach

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It's not a Linear Order, it's a Heirarchy. The standard system goes something like (top is highest priority):

Parenthesis
Negation (the unary - operator)
Exponentiation/Roots
Multiplication/Division
Addition/Subtraction

And, if one gets into programming, below this comes the bitwise shifting operations, than the comparative operators, than the bitwise logical operators, than the various logical operators.
 
Apr 2, 2008 at 1:31 AM Post #14 of 39

goldenratiophi

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Quote:

Originally Posted by Arainach /img/forum/go_quote.gif
Parenthesis
Negation (the unary - operator)
Exponentiation/Roots
Multiplication/Division
Addition/Subtraction



huh? Negation is just multiplication by -1. If negation is to be read first then you'd have -5^2 = 25. However we write -5^2 = -25 and (-5)^2 = 25. Unless I'm misinterpreting what you mean by negation...
 
Apr 2, 2008 at 1:37 AM Post #15 of 39

K2Grey

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I thought negation was used for like, boolean operations. Granted in that case it's unclear to me how it would interact with multiplications and divisions and so on. Ahh, math, you can get ridiculously complicated.
 

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