GCSE Maths Practice: decimals

Question 8 of 10

This question practises rounding decimals to a given place value. Understanding how to round accurately helps you estimate, simplify answers, and present results clearly in exams and real-life contexts.

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\( \begin{array}{l}\textbf{Round } 3.476 \textbf{ to 1 decimal place.}\end{array} \)

Choose one option:

When rounding decimals, underline the digit you’re rounding to and look at the next digit to decide whether to round up or keep the same. Always check if the question asks for decimal places or significant figures!

Rounding Decimals

Rounding helps simplify numbers while keeping them close to their original value. It’s used in estimating, money calculations, measurements, and data presentation. The key is understanding which digit controls the rounding decision.

Step-by-Step Method

  1. Underline the digit you’re rounding to (in this case, the tenths place).
  2. Look at the digit immediately to its right (the hundredths place).
  3. If that digit is 5 or more, increase the underlined digit by 1.
  4. If it’s less than 5, keep the underlined digit the same.
  5. Remove all digits to the right of the rounded place.

Worked Examples

Example 1: Round 4.32 to 1 decimal place.
Look at the second decimal digit (2). It’s less than 5 → answer = 4.3.

Example 2: Round 6.78 to 1 decimal place.
Next digit is 8 (≥5) → answer = 6.8.

Example 3: Round 2.445 to 2 decimal places.
Next digit is 5 → answer = 2.45.

Example 4: Round 7.499 to 1 decimal place.
Next digit is 9 → answer = 7.5.

Common Mistakes

  • Rounding too early: Only round at the end of a calculation unless instructed.
  • Confusing decimal places and significant figures: Decimal places count after the decimal point; significant figures count from the first non-zero digit.
  • Forgetting trailing zeros: In money, always show two decimal places (e.g. £3.50, not £3.5).

Real-Life Applications

Rounding is vital in real-life situations such as:
• Prices: £3.476 becomes £3.48 for accuracy or £3.50 for simplicity.
• Measurement: A board 3.476 m long can be recorded as 3.5 m.
• Science: Experimental data is often rounded to an appropriate precision.

FAQs

1. What’s the difference between rounding and truncating?
Rounding adjusts the last kept digit up or down. Truncating simply cuts off without adjusting.

2. What if the digit to check is exactly 5?
In GCSE Maths, you round up (e.g. 3.45 → 3.5).

3. When should I round to 2 or more decimal places?
Usually in money, measurements, or scientific contexts where precision matters.

Study Tip

Practise rounding to different places (1, 2, or 3 decimal places) to spot how accuracy changes. Try 3.476, 3.4761, and 3.4769 — the difference may seem small but matters in science and finance.

Mastering rounding builds accuracy and confidence for exams and real-world problem solving.