Pre-Algebra · Grades 6 to 8
Order of operations
Which calculation comes first in an expression.
The idea
The order of operations is the list of rules that says which calculation to do first. Without a fixed order, the same expression could give different answers.
The order is: parentheses, exponents, multiplication and division (left to right), then addition and subtraction (left to right). The memory aid PEMDAS matches this order.
Worked examples
- How to Use the Order of Operations (PEMDAS) Work through 4 + 3 x 2^2 - 6 / 3 in four steps. See which operation goes first, why each step is allowed, and the order mistakes to avoid.
- How to Evaluate an Algebraic Expression Evaluate 2x^2 + 3x - 1 when x = 3. Substitute the value, follow the order of operations, and see the mistakes that cost marks.
- How to Add and Subtract Negative Numbers Work out -7 + 3 - (-4) with the number line. Four steps, the reasons for each move, and the sign mistakes to avoid.
Practice this topic
4 problems with answers.