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GCSE Maths / Edexcel

Converting fractions, decimals, and percentages

Convert between fractions, decimals, and percentages, including common equivalences and fractions out of 100.

Number and Place ValueFoundation and HigherGrades 3 to 6Focused skill

Curriculum path: GCSE Maths > Edexcel > Number > Fractions, decimals, and percentages > Conversions

Pearson Edexcel GCSE Maths number: interchange between fractions, decimals, and percentages.

Practise this topicUpload your answerAsk AI to explain thisTry exam-style questions
Revision notes

Theory, examples, and quick checks.

Keep the method short, then practise straight away. This note is written for GCSE Maths Edexcel students who need clear working and reliable method marks.

Theory

Percent means out of 100. For example, 37% means 37 / 100.

To change a decimal to a percentage, multiply by 100.

To change a percentage to a decimal, divide by 100.

To change a percentage to a fraction, write it over 100 and simplify.

To change a fraction to a decimal, divide the numerator by the denominator.

Some common conversions should become automatic: 1 / 2 = 0.5 = 50%, 1 / 4 = 0.25 = 25%, 3 / 4 = 0.75 = 75%, and 1 / 5 = 0.2 = 20%.

Key ruleDecimal to percentage: x100. Percentage to decimal: divide by 100.

Worked examples

Decimal to percentage

Write 0.37 as a percentage.

  1. Multiply by 100.
  2. 0.37 x 100 = 37.

Answer: 37%

Percentage to fraction

Write 35% as a fraction in its simplest form.

  1. 35% = 35 / 100.
  2. Divide numerator and denominator by 5.
  3. 35 / 100 = 7 / 20.

Answer: 7 / 20

Fraction to percentage

Write 3 / 8 as a percentage.

  1. 3 / 8 = 0.375.
  2. 0.375 x 100 = 37.5.

Answer: 37.5%

Common mistakes

  • Dividing by 100 when changing a decimal to a percentage.
  • Forgetting to simplify a percentage written as a fraction.
  • Writing 0.37% instead of 37%.
  • Rounding a fraction-to-decimal conversion when the exact percentage is needed.

Quick exercise

Try these before moving to the exam-style questions.

  1. Write 0.64 as a percentage.
  2. Write 18% as a decimal.
  3. Write 45% as a fraction in simplest form.
  4. Write 3 / 4 as a percentage.
  5. Write 0.125 as a percentage.
Exam-style questions

Practise the same skill at three levels.

These are original GCSE-style questions with mark schemes, common wrong answers, and AI marking guidance so feedback stays close to exam expectations.

Basic GCSE styleFoundationNon-calculator2 marks

Write 0.72 as a percentage.

decimal to percentagefdp conversionsfoundation number
Standard exam styleFoundation and HigherEither3 marks

Write 7 / 20 as a decimal and as a percentage.

fraction to decimalfraction to percentagefdp conversions
ChallengeHigherNon-calculator3 marks

Put 0.6, 7 / 12, and 58% in ascending order.

ordering fdpfraction decimal percentagehigher reasoning