1.4: Order of Operations
What if you had a mathematical expression with multiple operations like
Watch This
CK12 Foundation: 0104S Evaluate Algebraic Expressions with Grouping Symbols
Guidance
Look at and evaluate the following expression:
How many different ways can we interpret this problem, and how many different answers could someone possibly find for it?
The simplest way to evaluate the expression is simply to start at the left and work your way across:
This is the answer you would get if you entered the expression into an ordinary calculator. But if you entered the expression into a scientific calculator or a graphing calculator you would probably get 29 as the answer.
In mathematics, the order in which we perform the various operations (such as adding, multiplying, etc.) is important. In the expression above, the operation of multiplication takes precedence over addition, so we evaluate it first. Let’s rewrite the expression, but put the multiplication in brackets to show that it is to be evaluated first.
First evaluate the brackets:
When we have only addition and subtraction, we start at the left and work across:
Algebra students often use the word “PEMDAS” to help remember the order in which we evaluate the mathematical expressions: Parentheses, Exponents, Multiplication, Division, Addition and Subtraction.
Order of Operations
 Evaluate expressions within Parentheses (also all brackets
[ ] and braces { }) first.  Evaluate all Exponents (terms such as
32 orx3 ) next.  Multiplication and Division is next  work from left to right completing both multiplication and division in the order that they appear.
 Finally, evaluate Addition and Subtraction  work from left to right completing both addition and subtraction in the order that they appear.
The first step in the order of operations is called parentheses, but we include all grouping symbols in this step—not just parentheses
Example A
Evaluate the following:
a)
b)
c)
Each of these expressions has the same numbers and the same mathematical operations, in the same order. The placement of the various grouping symbols means, however, that we must evaluate everything in a different order each time. Let's look at how we evaluate each of these examples.
a) This expression doesn't have parentheses, exponents, multiplication, or division. PEMDAS states that we treat addition and subtraction as they appear, starting at the left and working right (it’s NOT addition then subtraction).
b) This expression has parentheses, so we first evaluate
c) An expression can contain any number of sets of parentheses. Sometimes expressions will have sets of parentheses inside other sets of parentheses. When faced with nested parentheses, start at the innermost parentheses and work outward.
Brackets may also be used to group expressions which already contain parentheses. This expression has both brackets and parentheses. We start with the innermost group:
Example B
Evaluate the following:
a)
b)
a) There are no grouping symbols. PEMDAS dictates that we multiply and divide first, working from left to right:
b) First, we evaluate the expression inside the parentheses:
We can also use the order of operations to simplify an expression that has variables in it, after we substitute specific values for those variables.
Example C
Use the order of operations to evaluate the following:
a)
b)
a) The first step is to substitute the value for
(Note:
Follow PEMDAS  first parentheses. Inside parentheses follow PEMDAS again.
b) The first step is to substitute the value for
Follow PEMDAS: we cannot simplify the expressions in parentheses, so exponents come next.
In part (b) we left the parentheses around the negative numbers to clarify the problem. They did not affect the order of operations, but they did help avoid confusion when we were multiplying negative numbers.
Graphing Calculators
A graphing calculator is a very useful tool in evaluating algebraic expressions. Like a scientific calculator, a graphing calculator follows PEMDAS. In this section we will explain two ways of evaluating expressions with the graphing calculator.
Example D
Evaluate
Method 1: Substitute for the variable first. Then evaluate the numerical expression with the calculator.
Substitute the value
Input this in the calculator just as it is and press [ENTER]. (Note: use
The answer is 13.
Method 2: Input the original expression in the calculator first and then evaluate.
First, store the value
The answer is 13.
The second method is better because you can easily evaluate the same expression for any value you want. For example, let’s evaluate the same expression using the values
For \begin{align*}x = 2\end{align*}
The answer is 62.
For \begin{align*}x = \frac { 2 } { 3 }\end{align*}
The answer is 13.21, or \begin{align*} \frac { 1070 } { 81 }\end{align*}
Note: On graphing calculators there is a difference between the minus sign and the negative sign. When we stored the value negative three, we needed to use the negative sign which is to the left of the [ENTER] button on the calculator. On the other hand, to perform the subtraction operation in the expression we used the minus sign. The minus sign is right above the plus sign on the right.
Watch this video for help with the Examples above.
CK12 Foundation: Evaluate with Grouping Symbols
Vocabulary
 Algebra students often use the word “PEMDAS” to help remember the order in which we evaluate the mathematical expressions: Parentheses, Exponents, Multiplication, Division, Addition and Subtraction.
Order of Operations
 Evaluate expressions within Parentheses (also all brackets \begin{align*}[ \ ]\end{align*}
[ ] and braces { }) first.  Evaluate all Exponents (terms such as \begin{align*}3^2\end{align*}
32 or \begin{align*}x^3\end{align*}x3 ) next.  Multiplication and Division is next  work from left to right completing both multiplication and division in the order that they appear.
 Finally, evaluate Addition and Subtraction  work from left to right completing both addition and subtraction in the order that they appear.
 The first step in the order of operations is called parentheses, but we include all grouping symbols in this step—not just parentheses \begin{align*}( )\end{align*}
() , but also square brackets \begin{align*}[ \ ]\end{align*}[ ] and curly braces { }.
 Sometimes expressions will have sets of parentheses inside other sets of parentheses. These are called nested parentheses.
Guided Practice
Use the order of operations to evaluate the following:
a) \begin{align*}(3 \times 5)  (7 \div 2)\end{align*}
b) \begin{align*} 2  (t  7)^2 \times (u^3  v)\end{align*}
Solutions:
a) First, we evaluate the expressions inside parentheses: \begin{align*}3 \times 5 = 15\end{align*}
\begin{align*} (3 \times 5)  (7 \div 2) &= 15  3.5\\ &= 11.5\end{align*}
Note that adding parentheses didn’t change the expression in part c, but did make it easier to read. Parentheses can be used to change the order of operations in an expression, but they can also be used simply to make it easier to understand.
b) The first step is to substitute the values for \begin{align*}t, \ u,\end{align*}
\begin{align*}2  (19  7)^2 \times (4^3  2)\end{align*}
Follow PEMDAS:
\begin{align*}& 2  (19  7)^2 \times (4^3  2) \qquad \text{Evaluate parentheses:} \ (19  7) = 12; \ (4^3  2) = (64  2) = 62\\ & = 2  12^2 \times 62 \qquad \qquad \quad \ \text{Evaluate exponents:} \ 12^2 = 144\\ & = 2  144 \times 62 \qquad \qquad \quad \ \text{Multiply:} \ 144 \times 62 = 8928\\ & = 2  8928 \qquad \qquad \qquad \quad \text{Subtract.}\\ & = 8926\end{align*}
Part (b) in the last example shows another interesting point. When we have an expression inside the parentheses, we use PEMDAS to determine the order in which we evaluate the contents.
Practice
 Evaluate the following expressions involving variables.

\begin{align*}2y^2\end{align*}
2y2 when \begin{align*}x = 1\end{align*}x=1 and \begin{align*}y = 5\end{align*}y=5 
\begin{align*}3x^2 + 2x + 1\end{align*}
3x2+2x+1 when \begin{align*}x = 5\end{align*}x=5

\begin{align*}2y^2\end{align*}
 Use the order of operations to evaluate the following expressions.

\begin{align*}2 + 7 \times 11  12 \div 3\end{align*}
2+7×11−12÷3

\begin{align*}2 + 7 \times 11  12 \div 3\end{align*}
 Evaluate the following expressions involving variables.
 \begin{align*}(y^2  x)^2\end{align*} when \begin{align*}x = 2\end{align*} and \begin{align*}y = 1\end{align*}
For 46, use the order of operations to evaluate the following expressions.
 \begin{align*}8  (19  (2 + 5)  7)\end{align*}
 \begin{align*}(3 + 7) \div (7  12) \end{align*}
 \begin{align*}(4  1)^2 + 3^2 \cdot 2\end{align*}
For 710, insert parentheses in each expression to make a true equation.
 \begin{align*}5  2 \times 6  5 + 2 = 5\end{align*}
 \begin{align*}12 \div 4 + 10  3 \times 3 + 7 = 11\end{align*}
 \begin{align*}22  32  5 \times 3  6 = 30\end{align*}
 \begin{align*}12  8  4 \times 5 = 8\end{align*}
For 1112, evaluate each expression using a graphing calculator.
 \begin{align*}x^2 + 2x  xy\end{align*} when \begin{align*}x = 250\end{align*} and \begin{align*}y = 120\end{align*}
 \begin{align*}(xy  y^4)^2\end{align*} when \begin{align*}x = 0.02\end{align*} and \begin{align*}y = 0.025\end{align*}
Brackets
Brackets [ ], are symbols that are used to group numbers in mathematics. Brackets are the 'second level' of grouping symbols, used to enclose items already in parentheses.Expression
An expression is a mathematical phrase containing variables, operations and/or numbers. Expressions do not include comparative operators such as equal signs or inequality symbols.Grouping Symbols
Grouping symbols are parentheses or brackets used to group numbers and operations.nested parentheses
Nested parentheses describe groups of terms inside of other groups. By convention, nested parentheses may be identified with other grouping symbols, such as the braces "{}" and brackets "[]" in the expression . Always evaluate parentheses from the innermost set outward.Operations
Operations are actions performed on variables, constants, or expressions. Common operations are addition, subtraction, multiplication, and division.Parentheses
Parentheses "(" and ")" are used in algebraic expressions as grouping symbols.PEMDAS
PEMDAS (Please Excuse My Daring Aunt Sally) is a mnemonic device used to help remember the order of operations: Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.Real Number
A real number is a number that can be plotted on a number line. Real numbers include all rational and irrational numbers.Image Attributions
Description
Learning Objectives
Here you'll learn how to apply the order of operations to decide which operations take precedence over others when evaluating algebraic expressions.