GCSE Maths Practice: decimals

Question 9 of 10

This question helps you practise rounding decimals — an essential GCSE Maths skill for estimation, measurement, and checking accuracy. It focuses on rounding to one decimal place, which means keeping one digit after the decimal point.

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\( \begin{array}{l}\textbf{Round } 3.476 \textbf{ to one decimal place.}\end{array} \)

Choose one option:

To round decimals: find the digit you’re rounding to, check the next one, and decide whether to round up (5–9) or keep the same (0–4). Always write the result with the same number of decimal places required.

Understanding Rounding Decimals

Rounding helps simplify numbers so they are easier to read or estimate. In GCSE Maths, you’ll often be asked to round measurements, answers, or data values to a specific number of decimal places or significant figures. Rounding is especially important in everyday contexts such as money, distance, and time, where exact precision isn’t always necessary.

When rounding to one decimal place, you keep only one digit after the decimal point (the tenths place). The digit immediately after that (the hundredths place) tells you whether to round up or down.

Step-by-Step Method

  1. Identify the place value you need to round to — in this case, tenths.
  2. Look at the next digit (hundredths place). If it is 5 or more, increase the tenths digit by 1. If it’s less than 5, leave it as it is.
  3. Drop all remaining digits after the one you’re keeping.
  4. Make sure to keep the decimal point in the correct place.

For example:

  • 3.476 → 3.5 (7 rounds up)
  • 4.321 → 4.3 (2 rounds down)
  • 2.649 → 2.6 (4 rounds down)
  • 5.95 → 6.0 (5 rounds up)

Worked Examples

Example 1: Round 7.842 to one decimal place.
Hundredths digit = 4 → round down → 7.8.

Example 2: Round 9.276 to one decimal place.
Hundredths digit = 7 → round up → 9.3.

Example 3: Round 12.04 to one decimal place.
Hundredths digit = 4 → round down → 12.0.

Example 4: Round 0.68 to one decimal place.
Hundredths digit = 8 → round up → 0.7.

Common Mistakes

  • Incorrect rounding direction: Students sometimes round down when they should round up if the next digit is exactly 5.
  • Changing place value: Forgetting to keep the decimal in the same position can lead to misplaced digits (e.g. writing 35 instead of 3.5).
  • Too many decimal places: After rounding, remove all digits beyond the one required.

Real-Life Applications

Rounding appears in countless real-world scenarios. Shops often round prices to the nearest penny; scientists round measurements to reflect the precision of their instruments; and exam answers are frequently rounded to one or two decimal places for consistency. In finance, £3.476 might be displayed as £3.48, while a distance of 3.476 km could be reported as 3.5 km.

Knowing how to round quickly and accurately helps with estimation, budgeting, and data presentation. It’s also essential for understanding significant figures and limits of accuracy in higher-level GCSE topics.

FAQs

1. What does 'to one decimal place' mean?
It means keeping one digit after the decimal point — the tenths place.

2. What if the next digit is exactly 5?
Always round up. For example, 2.35 becomes 2.4.

3. What’s the difference between rounding and truncating?
Truncating means cutting off digits without adjusting the last one. Rounding adjusts it properly based on the next digit.

4. Why is rounding important?
It makes data easier to read, estimate, and compare, especially in measurements, surveys, or experiments.

Study Tip

When practising rounding, write the digits vertically and underline the place value you’re keeping. Then circle the next digit to decide if it rounds up or down. Doing this repeatedly will make you faster and more confident in exams.

Mastering rounding ensures you can present answers clearly and consistently across all GCSE Maths questions — from calculations to data analysis and measurement.