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MathidiaMathematics Academy
Calculations and problem solving
Lesson 13 of 75
Standard practice

Order of operations

Objective. Apply BIDMAS correctly to numerical expressions.

  1. 1. Learn
  2. 2. Worked example
  3. 3. Practice
  4. 4. Feedback
  5. 5. Continue

Learn: the key idea

The order of operations is the agreed order for calculating: Brackets, Indices (powers and roots), Division and Multiplication from left to right, then Addition and Subtraction from left to right — BIDMAS. For example, 6 + 4 × 3 = 6 + 12 = 18, not 30. And (6 + 4) × 3 = 30, because the brackets come first.

Worked example

Use the order of operations (BIDMAS) to work out 6 + 4 × 3 − (8 − 5)².

Array of 4 rows by 3 columns
  1. 1Brackets first: 8 − 5 = 3.
  2. 2Indices: 3² = 9.
  3. 3Multiplication: 4 × 3 = 12.
  4. 4Then left to right: 6 + 12 − 9 = 9.

Answer: 9

Concept mastery

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Practice

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Common mistake. Pupils often work simply from left to right, so 6 + 4 × 3 becomes 30. Find any brackets and multiplication or division first, then add and subtract.

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