In life, the order in which we do things is important. For example, we put on socks then shoes, rather than shoes and then socks.
The same goes for solving math problems with more than one operation. An operation is a mathematical process, such as addition, subtraction, multiplication or division. Other operations include raising a number to a power and taking a root of a number. An ‘operator’ is a symbol that indicates the type of operation, such as +, –, × or ÷.
There are a number of conventions (rules) which need to be followed in order to solve these problems correctly. The order goes:
Step 1: Do operations inside grouping symbols such as round parentheses (...), square parentheses [...], braces {...} or absolute values $\left|...\right|$|...|.
Step 2: Do exponents (powers) and square roots.
Step 3: Do multiplication and division going from left to right.
Step 4: Do addition and subtraction going from left to right.
Evaluate: $\left(48\div12+5\right)\times3$(48÷12+5)×3
Think: We need to simplify the problem by using our order of operation rules. First, we perform any operations inside the parentheses; division first followed by addition. Then we perform any other multiplication or division that is remaining, working from left to right.
Do:
$\left(48\div12+5\right)\times3$(48÷12+5)×3 | $=$= | $\left(4+5\right)\times3$(4+5)×3 |
$=$= | $9\times3$9×3 | |
$=$= | $27$27 |
Evaluate: $48-6\times\left(8-4\right)$48−6×(8−4)
Think: Using our order of operations, we want to first perform the subtraction in the parentheses. We then want to evaluate the multiplication. Finally, we can subtract the product from $48$48.
Do:
$48-6\times\left(8-4\right)$48−6×(8−4) | $=$= | $48-6\times4$48−6×4 |
$=$= | $48-24$48−24 | |
$=$= | $24$24 |
Evaluate $-18+21\div7$−18+21÷7
Evaluate $\left(-14\right)\div2-10\div\left(-2\right)$(−14)÷2−10÷(−2)