Rounding to Significant Figures

This example resource shows pupils what significant figures are and how to round numbers to either one or two significant figures. The numbers 1508.06 and 0.01704 and shown and labelled according to their significant figures. Then the numbers 3874m 6.254 and 0.07104 are rounded to 1 and 2 significant figures.

What Are Significant Figures?

Significant figures help us express numbers with the right level of accuracy, particularly in maths and science.

What Is a Significant Figure?

A significant figure is any digit that contributes to a number’s precision. Here’s how to identify them:
✔ All nonzero digits are significant (e.g., 1, 5, 9).
✔ Zeros between nonzero digits are significant (e.g., 205 has three significant figures).
✔ Trailing zeros in a decimal are significant (e.g., 3.500 has four significant figures).
❌ Leading zeros are not significant—they only indicate place value (e.g., 0.0025 has two significant figures: 2 and 5).

📌 Example:

• 1508.06 has six significant figures.
• 0.01704 has four significant figures, as the leading zeros are not significant.

Why Are Significant Figures Important?

Using the correct number of significant figures prevents misleading results. They are important in:
✔ Scientific measurements – Avoiding overstated precision.
✔ Large number comparisons – Simplifying values for easy understanding.
✔ Maths and statistics – Keeping results accurate in approximations and rounding.

How to Round to Significant Figures

1️⃣ Identify the first significant figure.
2️⃣ Count the required number of significant figures.
3️⃣ Look at the next digit – round up if 5 or more, down if less.
4️⃣ Adjust trailing digits accordingly (replace with zeros for whole numbers, trim in decimals).

Examples:

• 3875 → 4000 (1 significant figure)
• 6.254 → 6.3 (2 significant figures)
• 0.07109 → 0.071 (2 significant figures)

Why Teach Significant Figures?

Significant figures help students:
✔ Understand precision in measurements – Avoiding misleading accuracy.
✔ Interpret data efficiently – Making large and small numbers easier to compare.
✔ Develop essential rounding skills – Useful for science, engineering, and further maths.

What’s Included?

📝 Step-by-step explanations – How to identify and round significant figures.
📊 Worked examples – Demonstrates key rules, including handling zeros.
🎯 Visual guides – Clear formatting to aid understanding.
📥 Printable PDF Format – Ready to use for lessons or revision.

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Browse our extensive collection of worksheets, tailored to help students master rounding concepts. All worksheets are downloadable in PDF format, ensuring easy access for classroom and home use.