Primary 5 Four Operations
Keywords
- Expression
- Numbers and operation signs to work out.
- BODMAS
- Brackets, Orders, Division and Multiplication, Addition and Subtraction.
- Orders
- Powers such as squares; introduced here only to explain the acronym.
- Equal priority
- Division and multiplication share a level; addition and subtraction share a level. Work left to right within each level.
The four operations together
Addition (+), subtraction (−), multiplication (×) and division (÷) can appear in one expression. Decide the order before calculating.
Read the operation signs
20 − 12 ÷ 3 + 2 × 4
There are four operations here. The division and multiplication must be done before the subtraction and addition.
See worked example
Work out 20 − 12 ÷ 3 + 2 × 4.
- Divide and multiply first: 12 ÷ 3 = 4 and 2 × 4 = 8.
- The expression becomes 20 − 4 + 8.
- Work left to right: 20 − 4 = 16, then 16 + 8 = 24.
Answer: 24.
Try together
Work out 18 + 12 ÷ 3 − 2 × 4.
Reveal the answer
18 + 4 − 8 = 14.
Introduce BODMAS
BODMAS is a reminder for the order: Brackets, Orders, Division and Multiplication, then Addition and Subtraction. At the same level, work from left to right.
Choose an expression
5 + 3 × 10
Step 0 of 2
Answer: 35
See worked example
Work out (6 + 12 ÷ 3) × 2.
- Inside the brackets, divide first: 12 ÷ 3 = 4, so the expression becomes (6 + 4) × 2.
- Add inside the brackets: 6 + 4 = 10, giving 10 × 2.
- Multiply: 10 × 2 = 20.
Answer: 20.
Try together
Work out (8 + 16 ÷ 4) × 3.
Reveal the answer
(8 + 4) × 3 = 12 × 3 = 36.