What is important to know about Order of operations (BIDMAS)?

I – Indices (powers and roots).

What is important to know about Order of operations (BIDMAS)?

DM – Division and Multiplication, left to right.

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Number · Foundation & Higher

Order of operations (BIDMAS)

BIDMAS tells you the order in which to do operations: Brackets, Indices, Division and Multiplication (left to right), then Addition and Subtraction (left to right).

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Key facts to remember

1B – Brackets first.
2I – Indices (powers and roots).
3DM – Division and Multiplication, left to right.
4AS – Addition and Subtraction, left to right.
5Division and multiplication have equal priority (same for + and −).
6A fraction bar acts like brackets over both the numerator and denominator.

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Worked examples

Example 1

Work out 3 + 4 × (5 − 2)².

Working

Brackets: 5 − 2 = 3
Indices: 3² = 9
Multiplication: 4 × 9 = 36
Addition: 3 + 36 = 39

Answer39

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Common mistakes

✗Doing addition before multiplication.

✗Applying powers to the wrong part of an expression, e.g. treating −3² as 9 instead of −9.

✗Forgetting brackets imposed by a fraction bar.

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Exam tips

✓Rewrite the calculation step by step, showing each BIDMAS stage.

✓Use brackets generously in your working to avoid ambiguity.

✓On a calculator, always use brackets for complex expressions.

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