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Recurring decimals to fractions – GCSE Maths

Higher · Grade 6 · Non-calculator

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Turn a recurring decimal such as 0.4545… into an exact fraction using a short algebra trick. It is Higher only, aimed at grade 6. Free questions with answers are on this page. Worked examples show each line before you try the questions.

A recurring decimal such as or is a fraction in disguise. The method is algebra: let equal the decimal, multiply by , or until the repeating block lines up, subtract, and divide. One repeating digit: . Two repeating digits: . A delay before the repeat () needs two different multiplications so the non-repeating part cancels.

Simplify the fraction. , not left unsimplified. The reverse (fraction to recurring decimal) is long division of the numerator by the denominator. A terminating decimal is a fraction whose denominator's primes are only and .

Call the decimal , multiply to shift one full repeating block, subtract so the tail cancels, then simplify. One repeating digit uses ; two digits . A non-repeating starter such as needs both and .

Objectives

Key points

Worked examples

Example 1

Convert 0.777... to a fraction in its simplest form.

2 marks

  1. Identify the repeating block: the single digit 7 repeats.
  2. Place the repeating digit over 9: 7/9.
  3. 7/9 cannot be simplified further, so the final fraction is 7/9.

Answer: 7/9

Common slips
  • Slip: Treat 0.777... as 7/10. One repeating digit means a denominator of 9, not 10.
  • Slip: Write 777/1000. 777/1000 truncates the recurring decimal after three places.
  • Slip: Round the answer to 0.78. Exact form requires a fraction, not a rounded decimal.

Example 2

Convert 0.121212... to a fraction in its simplest form.

2 marks

  1. Identify the repeating block: the two digits 12 repeat.
  2. Place the block over 99 to get 12/99.
  3. Divide numerator and denominator by their common factor 3 to get 4/33.

Answer: 4/33

Common slips
  • Slip: Treat the decimal as terminating: 12/100. A two-digit repeating block goes over 99, not 100.
  • Slip: Place the block over 9 to get 12/9. Two repeating digits require 99 on the bottom.
  • Slip: Leave 12/99 uncancelled. Always reduce fractions to simplest form.

Example 3

Use algebra to write 0.636363... as a fraction in its simplest form.

3 marks

  1. Let x = 0.636363... Two digits repeat, so multiply by 100: 100x = 63.636363...
  2. Subtract x from 100x. The tails cancel: 99x = 63, so x = 63/99.
  3. Divide top and bottom by 9: 63/99 = 7/11.

Answer: 7/11

Common slips
  • Slip: Multiply by 10 to get 10x = 6.3636... The block has two digits, so multiply by 100. Multiplying by 10 does not line up the repeats.
  • Slip: Subtract and write 99x = 63.6 Both lines have the same tail, so it cancels and leaves a whole number: 99x = 63.
  • Slip: Leave the answer as 63/99 Cancel to simplest form: 63 ÷ 9 = 7 and 99 ÷ 9 = 11.

Questions and answers

GCSE Maths recurring decimals to fractions questions and answers. Try each one, then open the answer. Easy questions come first.

Question 1 Easy2 marks

Convert 0.444... to a fraction in its simplest form.

Show answer

Answer: 4/9

  1. One repeating digit 4 sits over 9.
  2. 4/9 cannot be simplified.
  • M1 — One repeating digit 4 sits over 9.
  • A1 — 4/9 cannot be simplified.

Question 2 Easy2 marks

Convert 0.222... to a fraction in its simplest form.

Show answer

Answer: 2/9

  1. One repeating digit 2 sits over 9.
  2. 2/9 cannot be simplified.
  • M1 — One repeating digit 2 sits over 9.
  • A1 — 2/9 cannot be simplified.

Question 3 Medium2 marks

Convert 0.454545... to a fraction in its simplest form.

Show answer

Answer: 5/11

  1. Two-digit repeating block 45 sits over 99.
  2. Divide numerator and denominator by 9: 45/99 = 5/11.
  • M1 — Two-digit repeating block 45 sits over 99.
  • A1 — Divide numerator and denominator by 9: 45/99 = 5/11.

Question 4 Medium2 marks

Convert 0.363636... to a fraction in its simplest form.

Show answer

Answer: 4/11

  1. Two-digit repeating block 36 sits over 99.
  2. Divide numerator and denominator by 9: 36/99 = 4/11.
  • M1 — Two-digit repeating block 36 sits over 99.
  • A1 — Divide numerator and denominator by 9: 36/99 = 4/11.

Question 5 Hard2 marks

Find the recurring decimal for the fraction 1/3.

Show answer

Answer: 0.3 recurring

  1. Perform division: 1 ÷ 3 = 0.333...
  2. The single digit 3 repeats indefinitely, written as 0.3 recurring.
  • M1 — Perform division: 1 ÷ 3 = 0.333...
  • A1 — The single digit 3 repeats indefinitely, written as 0.3 recurring.

Question 6 Hard2 marks

Find the recurring decimal for the fraction 2/9.

Show answer

Answer: 0.2 recurring

  1. Perform division: 2 ÷ 9 = 0.222...
  2. The single digit 2 repeats indefinitely, written as 0.2 recurring.
  • M1 — Perform division: 2 ÷ 9 = 0.222...
  • A1 — The single digit 2 repeats indefinitely, written as 0.2 recurring.

Question 7 Exam-style4 marks

Convert 0.545454... to a fraction in its simplest form.

Show answer

Answer: 6/11

  1. Let x = 0.545454... and 100x = 54.545454...
  2. Subtract: 99x = 54, so x = 54/99.
  3. Divide numerator and denominator by 9: 54 ÷ 9 = 6 and 99 ÷ 9 = 11.
  4. The simplified fraction is 6/11.
  • M1 — Set up subtraction 100x - x = 99x = 54
  • M1 — Write fraction as 54/99
  • M1 — Divide top and bottom by 9
  • A1 — Simplified fraction 6/11

Common mistakes

Most lost marks on this topic are one slip.

  1. Using 10 or 100 as the denominator for a repeating block

    Use 9 for one digit and 99 for two

  2. Leaving 45/99 when it still cancels

    Divide top and bottom by 9

  3. Rounding a recurring decimal that was asked for as a fraction

    Keep the cancelled fraction

Spot the slip

Ada says 0.777... equals 7/10 because she only looks at the first digit. Which fraction is exact?

  1. 7/9
  2. 7/10
  3. 777/1000
Show the slip

7/9 One repeating digit is a fraction with 9 on the bottom.

Exam tips

Printable worksheet

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Questions students ask

Is Recurring decimals to fractions Foundation or Higher?

Recurring decimals to fractions is Higher only, aimed at grade 6.

What is a common slip on Recurring decimals to fractions?

Using 10 or 100 as the denominator for a repeating block. Use 9 for one digit and 99 for two.

Where can I get Recurring decimals to fractions questions and answers?

The questions on this page are free. Open Show answer under each one, or download the worksheet PDF. Start free to practise this topic in the app.

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Last updated 9 November 2026.

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