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MathidiaMathematics Academy
Percentage change and finance
Lesson 13 of 75
Standard practice

Profit, loss and discount

Objective. Solve contextual percentage problems and justify decisions.

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

Learn: the key idea

Profit, loss and discount develops a connected mathematical idea rather than an isolated trick. Use multipliers to model repeated percentage change. Begin by representing the quantities or relationships, choose a rule that fits, justify each transformation, and finish by checking units, signs, scale and whether the answer is reasonable.

Worked example

Find 3 years simple interest on £500 at 4% per year.

£500.00
Money illustration for £500
  1. 1Identify the known information, the unknown and any conditions.
  2. 2Choose a diagram, table, graph or algebraic representation that exposes the structure.
  3. 3Apply the relevant rule one justified step at a time, keeping exact values where useful.
  4. 4Check by substitution, inverse reasoning or estimation. The result is £60.

Answer: £60

Concept mastery

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Practice

Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.

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Common mistake. A common error in profit, loss and discount is to copy a procedure without checking its conditions. Label the structure first and justify every sign, operation and unit.

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