# Rounding Significant Figures

Welcome to the Math Salamanders Rounding Significant Figures collection.

Here you will find a selection of free printable rounding Worksheets, which will help your child learn to round numbers to either 1, 2 or 3 significant figures.

## Rounding Significant Figures

### Rounding numbers to 1 significant figure (1SF)

When you are rounding a number to 1 significant figures, you are trying to reduce the number to a single digit and zeros (and possibly a decimal point) to indicate its place value.

How to round a number to 1 significant figure

Look at the 2nd significant digit that the number has.

In a decimal, the first significant digit is the first non-zero digit. The 2nd significant digit is the digit after the first.

• if it is less than 5 then round the number down by removing the rest of the number after the 1st significant digit and filling in with zeros;
• if it is 5 or more then round the number up by adding one on to the 1st digit and removing the rest of the number and filling in with zeros.

Examples

• 8726 rounds up to 9000, because the 2nd significant digit is a 7.
• 73.283 rounds down to 70 because the 2nd significant digit is a 3.
• 152 rounds up to 200 because the 2nd significant digit is a 5.
• 0.003826 rounds up to 0.004 because the 2nd significant digit is an 8.
• 0.60828 rounds down to 0.6 because the 2nd significant digit is a 0.

### Rounding numbers to 2 significant figures (2sf)

When you are rounding a number to 2 significant figures, you are trying to reduce the number to a two digits and zeros (and possibly a decimal point) to indicate its place value.

How to round a number to 2 significant figures

Look at the 3rd significant digit that the number has.

This is the digit which is two digits after the most significant digit.

• if it is less than 5 then round the number down by removing the rest of the number after the 2nd significant digit and filling in with zeros;
• if it is 5 or more then round the number up by adding one on to the 2nd significant digit and removing the rest of the number and filling in with zeros.

Examples

• 5271 rounds up to 5300, because the 3rd significant digit is a 7.
• 73.483 rounds down to 73 because the 3rd significant digit is a 4.
• 175 rounds up to 180 because the 3rd significant digit is a 5.
• 0.003826 rounds down to 0.0038 because the 3rd significant digit is a 2.
• 0.60828 rounds up to 0.61 because the 3rd significant digit is an 8.

### Rounding to 3 significant figures (3sf)

When you are rounding a number to 3 significant figures, you are trying to reduce the number to a 3 digits and zeros (and possibly a decimal point) to indicate its place value.

How to round a number to 3 significant figures

Look at the 4th significant digit that the number has.

• if it is less than 5 then round the number down by removing the rest of the number after the 3rd significant digit and filling in with zeros;
• if it is 5 or more then round the number up by adding one on to the 3rd significant digit and removing the rest of the number and filling in with zeros.

Examples

• 5261 rounds down to 5260, because the 4th significant digit is a 1.
• 73.285 rounds up to 73.3 because the 4th significant digit is an 8.
• 1805 rounds up to 1810 because the 4th significant digit is a 5.
• 0.003826 rounds up to 0.00383 because the 4th significant digit is a 6.
• 0.07284 rounds down to 0.0728 because the 4th significant digit is a 4.

### More Recommended Math Worksheets

Take a look at some more of our worksheets similar to these.

### Rounding to Significant Figures Online Quiz

Our quizzes have been created using Google Forms.

At the end of the quiz, you will get the chance to see your results by clicking 'See Score'.

This will take you to a new webpage where your results will be shown. You can print a copy of your results from this page, either as a pdf or as a paper copy.

For incorrect responses, we have added some helpful learning points to explain which answer was correct and why.

We do not collect any personal data from our quizzes, except in the 'First Name' and 'Group/Class' fields which are both optional and only used for teachers to identify students within their educational setting.

We also collect the results from the quizzes which we use to help us to develop our resources and give us insight into future resources to create.

This quiz tests your knowledge and ability to round off numbers to 1, 2 or 3 significant figures.

Fun Quiz Facts

• This quiz was attempted 829 times last academic year.
• The average (mean) score was 10 out of 15 marks.
• Can you beat the mean?

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