Boba Maths

Year 6 · Arithmetic skills · Skill 13A

Skill 13A: Order of operations (BIDMAS)

Use the order of operations with brackets, powers, multiplication, addition and subtraction.

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Each file is an editable Word document (.docx) with 25 questions in five columns. It opens in Word, Google Docs, Pages and LibreOffice, so you can change questions or add working space before printing.

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Worked examples

BIDMAS tells us the order to do a calculation with more than one operation, so everyone gets the same answer. Work through the letters in order.

Example 1

Brackets, indices and multiplication

50 − (3² + 4 × 5)

  1. Remember the order:
    LetterStands forDo it
    BBracketsfirst
    IIndices (powers, such as ²)second
    D MDivision and multiplicationthird, left to right
    A SAddition and subtractionlast, left to right
  2. Brackets first. Inside the brackets there is a power and a multiplication, so we use BIDMAS inside the brackets too. Indices first: 3² = 9.
    50 − (3² + 4 × 5)50 − (9 + 4 × 5)
  3. Still inside the brackets, multiplication before addition: 4 × 5 = 20.
    50 − (9 + 4 × 5)50 − (9 + 20)
  4. Add inside the brackets: 9 + 20 = 29.
    50 − (9 + 20)50 − 29
  5. Finally subtract: 50 − 29 = 21.

Answer: 21

Example 2

Multiplication before addition

7 + 6 × 4

  1. There are no brackets or indices. Multiplication comes before addition, even though the addition is written first: 6 × 4 = 24.
    7 + 6 × 47 + 24
  2. Now add: 7 + 24 = 31.

Answer: 31

Top tips

  • Say BIDMAS (or BODMAS) before you start.
  • Rewrite the calculation after each step so you can see what is left.
  • Division and multiplication are equal in rank: do them left to right. Addition and subtraction are the same.

Watch out for

  • Working left to right whatever the operations, so 7 + 6 × 4 becomes 52 instead of 31.
  • Forgetting that powers come before multiplication.

Try some questions

These are from the worksheet. Work each one out, then open it to check.

  1. 6 + 4 × 3 =
    Show the answer

    18

  2. 50 − 5² =
    Show the answer

    25

  3. 120 − 4³ =
    Show the answer

    56

  4. 400 − (6³ + 4 × 20) =
    Show the answer

    104

All arithmetic skills

Skill 1ASkill 1BSkill 2ASkill 2BSkill 3ASkill 4ASkill 4BSkill 5ASkill 5BSkill 6ASkill 6BSkill 6CSkill 6DSkill 7ASkill 8ASkill 9ASkill 10ASkill 10BSkill 10CSkill 11ASkill 11BSkill 11CSkill 12ASkill 14A

Arithmetic skills overview · Year 6 overview