Year 10 GCSE Maths Worksheet — 1, 2 & 3 Significant Figures (Age 15) — Large & Small Numbers

Instructions

This worksheet will help you practice rounding both large and small numbers to 1, 2, and 3 significant figures (s.f.). Read the rules below carefully before you begin.

A Quick Recap: The Rules of Significant Figures

• Rule 1: All non-zero digits (1-9) are always significant. (e.g., 123 has 3 s.f.)
• Rule 2: Zeros between non-zero digits are significant. (e.g., 5,007 has 4 s.f.)
• Rule 3: Zeros at the beginning of a number are NOT significant. They are just placeholders. (e.g., 0.0082 has 2 s.f.)
• Rule 4: Zeros at the end of a number are significant ONLY if there is a decimal point. (e.g., 24.0 has 3 s.f., but 2400 has 2 s.f.)

Rounding Reminders

• Find the last significant digit you need to keep.
• Look at the next digit to its right (the "decider" digit).
• If the decider is 5 or more, round your last digit up. If it's 4 or less, keep it the same.
• Replace any following digits before the decimal point with zeros as placeholders. (e.g., 48,123 to 2 s.f. is 48,000).

Part 1: How many significant figures?

For each number below, state how many significant figures it has.

Part 2: Rounding to 1 Significant Figure

Round the following numbers to 1 s.f.

Part 3: Rounding to 2 Significant Figures

Round the following numbers to 2 s.f.

Part 4: Rounding to 3 Significant Figures

Round the following numbers to 3 s.f.

Part 5: Mixed Practice

Complete the table by rounding each number to 1, 2, and 3 significant figures.

Answer Key

Part 1: How many significant figures?

1. 4
2. 2
3. 4
4. 4
5. 2
6. 2 (The trailing zeros are not significant as there is no decimal point.)

Part 2: Rounding to 1 Significant Figure

1. 9,000
2. 0.05
3. 7
4. 30,000

Part 3: Rounding to 2 Significant Figures

1. 3,500
2. 81
3. 0.0077
4. 5.1

Part 4: Rounding to 3 Significant Figures

1. 9,880
2. 45,600
3. 0.0123
4. 2.00

Part 5: Mixed Practice