In a math expression, multiplication and division takes place before addition and subtraction.

The Order of Operations and Variables:

Tip:

A good idea when working with many operations at a time is to do a little portion of the equation at a time, rewriting frequently. For example, do the portion within the parentheses and then rewrite the equation. Trying to do the entire equation at once can often lead to mistakes. Break it down into parts using the order of operations and do a little at a time.

What is the order of operations?

Operations are things like addition, subtraction, multiplication, and division. When you add two numbers together, you are performing the operation of addition on them. Similarly, when you multiply numbers together, you are performing the operation of multiplication.

The order of operations is the rule for what operations should be done first when there are several operations within the same equation.

The order of operations is like grammar rules for the language of math. It explains how to interpret an equation to mean what it is supposed to mean.

Applying the Order of Operations (PEMDAS)

The order of operations says that operations must be done in the following order: parentheses, exponents, multiplication, division, addition, and subtraction.

Parentheses

When there are parentheses, whatever is inside must be done first. The stuff inside the parentheses may also need to be broken down according to the order of operations as well. It is even possible to have parentheses within parentheses. In cases like this, work from the inside out.

Exponents

If there are exponents in the equation, these would be done next.

Multiplication and Division

Multiplication and division can be done together. In other words, it doesn’t matter if you do division or multiplication first, but they must be done after parentheses and exponents and before addition and subtraction.

Addition and Subtraction

Addition and subtraction also work together. You can do subtraction first, or you can do addition first. They are part of the same step, however, they can only be done after items in parentheses, exponents, and any multiplication and division.

PEMDAS

A frequently used expression in English to help students remember the order of operations is PEMDAS.

Another way to remember this is the phrase “Please Excuse My Dear Aunt Sally.”

Critical Thinking Challenge

Can you think of another phrase that could help you remember the order of operations?

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Remember to take it one step at a time and rewrite your equation after completing an operation. Doing this will help you keep track of what you’ve already done and make sure you don’t skip any steps.

Remember to continue to work on memorizing your single digit multiplication if they aren’t memorized yet. As you are beginning to see, we are using multiplication a lot in these lessons and they will be easier if you know your multiplication.

Additional Resources

• Khan Academy: Intro to order of operations (09:39 mins, Transcript)
• Khan Academy: Order of operations example (04:26 mins, Transcript)
• Khan Academy: Order of operations (PEMDAS) (05:19 mins, Transcript)

Practice Problems

Evaluate the following expression:

1. \(0\div4\times7+5^{2}\div5\times5 = ?\)
2. \(6 - 4 ^{2} \div 2 - 2^{3} + 3 = ?\)
3. \(6 \div 1 - \lgroup 7 - 5 \rgroup \times 3^{2} \times 7 = ?\)
4. \(7 + 2 \times 3^{3} + 12 \div 2 = ?\)
5. \(2^{3} \times 5 \div \lgroup 5 - 1 \rgroup \div \lgroup 2 - 1 \rgroup \times 6 = ?\)
6. \(5^{3} - \lgroup 5 \times 2 \rgroup^{2} - 2^{4} - 2^{3} = ?\)

What does a professional programmer usually do first to gain an understanding of a problem?

Is a set of well defined logical steps that must?