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When an expression contains more than one operation, you can get different answers depending on the order in which you solve the expression. Mathematicians have agreed on a certain order for evaluating expressions, so we all arrive at the same answers. We often use grouping symbols, like parentheses, to help us organize complicated expressions into simpler ones. Here's the order we use:
In Example 1, without any parentheses, the problem is solved by working from left to right and performing all the addition and subtraction. When parentheses are used, you first perform the operations inside the parentheses, and you'll get a different answer!
Example 1  Parenthesis
Without Parenthesis

With Parenthesis

8
 7 + 3 = 
8
 (7 + 3) = 
Example 2
Order of Operations

Explanation

2^{2} x 20/4  7 x 3 + 55 = 
Calculate the exponent 
4
x 20/4  7 x 3 + 55 =
4 x 5  21 + 55 = OR 80/4  21 + 55 = (4 x 5 and 80/4 both = 20) 
Working from left to right, do all multiplications
and divisions. When there are several of these operations in the same
term, the order within the term doesn't matter

20
 21 + 55 =

Add and subtract from left to right

54

The correct answer!

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