--- title: "Rounding to decimal places and significant figures" description: "Round numbers and measures to an appropriate degree of accuracy including to a specified number of decimal places or significant figures" canonical: https://lightmysky.com/learn/mathematics/rounding-to-decimal-places-and-significant-figures-mt_U9sme87C32 source: https://lightmysky.com/learn/mathematics/rounding-to-decimal-places-and-significant-figures-mt_U9sme87C32.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Rounding to decimal places and significant figures Round numbers and measures to an appropriate degree of accuracy including to a specified number of decimal places or significant figures Subject: Mathematics · Area: Number Representation & Place Value · Ages 11 to 13 Page: https://lightmysky.com/learn/mathematics/rounding-to-decimal-places-and-significant-figures-mt_U9sme87C32 ## Ready when they can - Round numbers to a given number of decimal places - Round numbers to a given number of significant figures - Choose an appropriate degree of accuracy for a given context ## Lesson: Rounding decimals and significant figures Every digit in a decimal has a place: tenths, hundredths, thousandths, and so on. Rounding means shortening a decimal to a set number of those places. To round to a certain number of decimal places, look at the digit right after your cut-off point. If it is 5 or more, the last digit you keep rounds up by one. If it is less than 5, that digit stays the same. Then everything after it is dropped. *(drawing: Rounding 4.2819 to 2 decimal places. The digit after the cut-off is 1, less than 5, so it stays 4.28.)* **Example.** Round 12.3746 km to 2 decimal places. Keep the tenths and hundredths digits: 3 and 7. The next digit, the thousandths digit, is 4. Since 4 is less than 5, the 7 stays a 7. The answer is 12.37 km. Significant figures are a different way to control accuracy. Start counting from the first digit that isn't zero, then count every digit after it, including digits after the decimal point. Rounding to 3 significant figures means keeping the first three of those digits. You still look at the next digit to decide whether to round up. **Example.** Round 12.3746 km to 3 significant figures. The first three significant figures are 1, 2, and 3. The next digit is 7. Since 7 is 5 or more, the 3 rounds up to 4. The answer is 12.4 km. **Tip.** Match your rounding to what the measurement is for. A recipe might only need whole grams, while a science reading might need 2 or 3 decimal places to be useful. More decimal places isn't automatically better. **Recap.** Look at the digit right after your cut-off point: 5 or more rounds the last digit up, below 5 leaves it the same. ## Practice 20 questions on this page, each with its working shown. ## Needs first - [Rounding to a required degree of accuracy](https://lightmysky.com/learn/mathematics/rounding-to-a-required-degree-of-accuracy-mt__casygEB85) ## Opens up - [Bounds and error in rounded values](https://lightmysky.com/learn/mathematics/bounds-and-error-in-rounded-values-mt_VVn1IXjkzn)