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Order of Addition, Subtraction


Date: 9/5/96 at 18:59:55
From: Anonymous
Subject: The Order of Addition, Subtraction

If an equation has both addition and subtraction in it, which do I 
solve first? An example is 24-3+9/3/3 or 7+4-3+1. Do you do all the
addition before the subtraction in the second example or do you just 
go left to right? In the first example do you do the division first, 
then the addition, then the subtraction? This is confusing for me. 

Thanks,
    Karla


Date: 9/5/96 at 20:24:48
From: Doctor Robert
Subject: Re: The Order of Addition, Subtraction

Please Excuse My Dear Aunt Sally or PEMDAS is one way to remember the
order of operations.  

P  stands for parentheses.  They should always be worked first.  
E  stands for exponents.  
MD stands for multiplication/division done reading from left to right.  
   One does not have priority over the other. 
AS stands for addition/subtraction reading from left to right.  
   One does not have priority over the other.

Your examples:  24-3+9/3/3 = 
                24-3+3/3=
                24-3+1=
                21+1=
                22

  7+4-3+1=
  11-3+1=
  8+1=
  9

I hope that this helps.

-Doctor Robert,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Algebra

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