AC9M4A01 • Practice

Unknown Values in Addition and Subtraction Equations

Read the quick preparation notes, then start when you are ready.

SkillrHub quiz practice is built for curriculum-aligned revision with answer feedback and a clear review path.

Quick preparation

  • The equals sign says both sides have the same value. The missing number can be anywhere in an addition or subtraction equation.
  • Use a part-part-whole or balance model. Addition and subtraction undo each other, so identify whether the unknown is a part or the whole.
  • You may swap addends without changing a sum. You cannot generally swap the numbers in a subtraction. Substitute your answer to check both sides.

SkillrHub Practice guide

Use this short shuffled practice set to check the skill, read feedback and review missed items. Repeat quiz practice to access more of the full question bank over time.

Model: The first journey is 4 + 7. Reversing those two jumps gives 7 + 4 and reaches the same point, 11.
  • Worked example: In □ − 28 = 46, the missing whole is 46 + 28 = 74. In 74 − □ = 46, the missing part is 74 − 46 = 28. Substituting either answer gives 74 − 28 = 46.
  • Common mistake: Do not always subtract the two visible numbers. First identify the role of the missing number and keep both sides of the equation equal.
  • Assessment guidance: Use this short shuffled attempt to practise. Repeat it to meet more questions from the full bank.
  • Review: Put your answer back into the original equation. Use a model or a property of addition or subtraction to explain why it works.
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