Estimate the value of $\dfrac{48.7\times9.12}{0.31}$.

Round each number to 1 significant figure: $50$, $9$, $0.3$. $50\times9=450$. $450\div0.3=4500\div3=1500$. Answer: 1500

Edexcel IGCSE 4MA1 Rounding and Bounds: Exam Questions & Answers

Edexcel IGCSE 4MA1 Rounding and Bounds: Exam Questions and Answers

Rounding and Bounds questions with full solutions for Pearson Edexcel International GCSE Mathematics A (4MA1), Higher tier. Read the 4 worked examples first, then cover each solution and redo it yourself.

4 worked examples

Higher tier · calculator allowed

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Question 1 of 5
Question 2 of 5
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Start with one question on rounding to significant figures. Stuck? Take a hint. No sign-in needed.

Round

34567

to 3 significant figures.

Choose your answer · keys 1–4

346

34570

34500

34600

What this topic covers

Rounding, estimation & standard form: Rounding to decimal places or significant figures and writing large/small numbers in standard form.
Rounding Numbers and Using a Calculator: Rounding to sig figs / d.p. and using GDC modes.
Upper and Lower Bounds 1: Error bounds on rounded measurements.
Upper and Lower Bounds 2: Bounds in calculations (area, speed).

Rounding and Bounds worked examples

Worked example 1: Estimating

Estimate the value of $\frac{48.7 \times 9.12}{0.31}$ .

Solution

Round each number to 1 significant figure: $50$ , $9$ , $0.3$ .
$50 \times 9 = 450$ .
$450 \div 0.3 = 4500 \div 3 = 1500$ .

4 steps

Tip: Dividing by 0.3 makes the answer bigger.

Worked example 2: Calculator work and rounding

Work out $\frac{\sqrt{12.5} + {3.1}^{2}}{4.7}$ , giving your answer to 3 significant figures.

Solution

$\sqrt{12.5} = 3.5355 \dots$ and ${3.1}^{2} = 9.61$ .
Numerator: $13.1455 \dots$ .
Divide by 4.7: $2.79692 \dots$ .
To 3 s.f.: 2.80.

5 steps

Tip: Keep full calculator values until the final step; the zero in 2.80 is significant.

Worked example 3: Bounds

A length is 6.4 m to 1 decimal place. Write down its lower and upper bounds.

Solution

Half of 0.1 is 0.05.
Lower bound 6.35 m, upper bound 6.45 m.

3 steps

Tip: The upper bound is not included, but is used in calculations.

Worked example 4: Bounds in a subtraction

$a = 12$ to the nearest integer and $b = 4.3$ to 1 d.p. Find the upper bound of $a - b$ .

Solution

For the largest difference use the largest $a$ and smallest $b$ .
$12.5 - 4.25 = 8.25$ .

3 steps · 1 to fill in

Tip: For subtraction and division, pair an upper bound with a lower bound.

Every question and worked example here is original, written for IGCSE Math Revision rather than copied from Pearson papers, and each answer was re-solved independently before publishing.

Questions students ask

Which Edexcel IGCSE Maths papers test rounding and bounds?

Either Higher tier paper, 1H or 2H, can test rounding and bounds: both cover the whole Pearson Edexcel International GCSE Mathematics A (4MA1) specification and both allow a calculator. Show your method, because most marks are for working.

Where can I practise more rounding and bounds questions?

In the IGCSE student hub: Unit 1 (Number) has more exam-style questions on this topic, each with a mark scheme. Practice starts with a 7-day free trial; the worked examples and questions on this page are free.

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Edexcel IGCSE 4MA1 Rounding and Bounds: Exam Questions and Answers

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What this topic covers

Rounding and Bounds worked examples

Worked example 1: Estimating

Solution

Worked example 2: Calculator work and rounding

Solution

Worked example 3: Bounds

Solution

Worked example 4: Bounds in a subtraction

Solution

Revise rounding and bounds for the exam

Questions students ask

Practise rounding and bounds with your progress saved

More Unit 1 topics: Number