Fractions, Decimals and Percentages

Convert fluently between fractions, decimals and percentages.

  • Define and explain Fractions, Decimals and Percentages in your own words
  • Use key terms such as Recurring decimal accurately
  • Apply what you have learned to new examples and questions
  • Avoid the common mistakes learners make with this topic

This lesson focuses on Fractions, Decimals and Percentages: convert fluently between fractions, decimals and percentages.

Definition: Fractions, Decimals and Percentages

Convert fluently between fractions, decimals and percentages.

Key ideas

Equivalent forms

1/2 = 0.5 = 50% — fractions, decimals and percentages are three ways of writing the same amount. Choosing the handiest form makes each calculation easier.

Place value

Each digit's value depends on its position: in 5,042 the 5 is worth five thousand and the 4 is worth forty. Zeros hold the other digits in place.

Key term — Recurring decimal: A decimal with a digit or group of digits that repeats forever, such as 0.333….

Worked example: Fractions, Decimals and Percentages

Write 3/8 as a decimal.

0.375 — 3 ÷ 8 = 0.375.

Answer: 0.375 — 3 ÷ 8 = 0.375.

Common mistakes
  • Dropping a decimal place 10% of 40 is 4, not 40 — divide by 10 to find ten per cent.
  • Adding before multiplying In 2 + 3 × 4 the answer is 14, not 20 — multiplication comes before addition in BIDMAS.

Practice

Round 7.846 to 2 decimal places.
Look at the third decimal digit.

7.85 — the third digit, 6, rounds the 4 up to 5.

Work out 2 + 3 × 4.
Multiply before you add.

14 — 3 × 4 = 12, then 2 + 12 = 14.

What is 25% of 80?
25% is one quarter.

20 — 80 ÷ 4 = 20.

Work out −4 + 9 − 3.
Move along the number line.

2 — −4 + 9 = 5, then 5 − 3 = 2.

Quick check

Fractions, Decimals and Percentages — quick check

Which of these best defines "Recurring decimal"?

A decimal with a digit or group of digits that repeats forever, such as 0.333….

List the factors of 24.

1, 2, 3, 4, 6, 8, 12, 24.
Key takeaways
  • Fractions, Decimals and Percentages: convert fluently between fractions, decimals and percentages.
  • Equivalent forms: 1/2 = 0.5 = 50% — fractions, decimals and percentages are three ways of writing the same amount.
  • Prime number: A whole number greater than 1 with exactly two factors: 1 and itself, such as 7 or 13.
  • Watch out for: dropping a decimal place