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Fractions, Decimals and Percentages

FoundationChallengeAQAEdexcelOCR

Master fractions, decimals and percentages for GCSE Maths with structured, exam-style practice. This Foundation resource covers converting between fractions, decimals and percentages and includes a complete mark scheme showing the steps examiners reward. Suitable for AQA, Edexcel and OCR. Free to download as a PDF. Percentages are out of 100, so 25% = 0.25 = ¼.

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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.

Topic overview

Fractions, decimals and percentages are three ways of writing the same proportion. Being able to move between them quickly is essential, because questions often mix the forms deliberately.

A fraction becomes a decimal by dividing the numerator by the denominator. A decimal becomes a percentage by multiplying by \(100\), and a percentage becomes a decimal by dividing by \(100\).

A small set of equivalents is worth knowing by heart: a half is \(0.5\) and 50 percent, a quarter is \(0.25\) and 25 percent, a fifth is \(0.2\) and 20 percent, and a tenth is \(0.1\) and 10 percent. Recognising these instantly saves time in ordering and comparison questions.

Revision notes

Converting between the forms

Fraction to decimal: divide the top by the bottom. Decimal to percentage: multiply by \(100\). Percentage to fraction: write it over \(100\) and simplify.

So \(\frac{3}{8} = 3 \div 8 = 0.375 = 37.5\%\), and \(45\% = \frac{45}{100} = \frac{9}{20}\).

Ordering mixed forms

Convert everything to the same form first, and decimals are usually easiest because they compare digit by digit.

To order \(\frac{2}{5}\), \(0.35\) and \(38\%\), convert to \(0.4\), \(0.35\) and \(0.38\), giving the order \(0.35\), \(38\%\), \(\frac{2}{5}\).

Equivalents worth memorising

Learn the common set: \(\frac{1}{2} = 0.5 = 50\%\), \(\frac{1}{4} = 0.25 = 25\%\), \(\frac{3}{4} = 0.75 = 75\%\), \(\frac{1}{5} = 0.2 = 20\%\), \(\frac{1}{10} = 0.1 = 10\%\), \(\frac{1}{3} = 0.333\ldots = 33.3\%\).

These appear constantly, and recognising them removes the need to calculate.

Key points

  • Divide the numerator by the denominator to get a decimal.
  • Multiply a decimal by 100 to get a percentage.
  • Divide a percentage by 100 to get a decimal.
  • Write a percentage over 100 to get a fraction, then simplify.
  • Convert to a common form before ordering.
  • Learn the common equivalents by heart.

Worked examples

Example 1

Write \(\frac{7}{20}\) as a decimal and a percentage.

Working

\[7 \div 20 = 0.35\]divide the numerator by the denominator
\[0.35 \times 100 = 35\%\]multiply the decimal by 100

Example 2

Write \(24\%\) as a fraction in its simplest form.

Working

\[\frac{24}{100}\]write the percentage over 100
\[= \frac{6}{25}\]divide top and bottom by 4

Example 3

Put \(0.62\), \(\frac{3}{5}\) and \(65\%\) in ascending order.

Working

\[\frac{3}{5} = 0.6 \text{ and } 65\% = 0.65\]convert everything to decimals
\[0.6 < 0.62 < 0.65\]compare the decimals
\[\frac{3}{5},\ 0.62,\ 65\%\]write the original forms in order

Common mistakes

  • Multiplying a percentage by 100 instead of dividing.

    45% is 0.45, not 4500. Dividing converts a percentage to a decimal.

  • Comparing fractions by their numerators.

    3/5 is larger than 5/9 even though 3 is smaller than 5. Convert before comparing.

  • Writing 0.4 as 4%.

    Multiply by 100 to get 40%. Losing the place value is a very common slip.

  • Leaving a fraction unsimplified.

    24/100 should be given as 6/25 when the simplest form is asked for.

Exam tips

  • Convert everything to decimals when ordering, since they compare most easily.
  • Learn the common equivalents so you do not have to calculate them.
  • Give the answer in the form the question asks for, not the form you worked in.
  • Simplify any fraction in a final answer.

Key terms

Equivalent
Different forms representing the same value.
Percentage
A proportion expressed out of 100.
Ascending order
Arranged from smallest to largest.
Simplest form
A fraction written with the smallest possible whole numbers.

Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.