National 5 Maths
Rounding

 Our generous sponsors 

Course content

  • Rounding to a given number of significant figures or decimal places.

Rules for significant figures

  • All non-zero digits are significant.
  • Zeros between non-zero digits are significant, because without them the value of the number would change, eg. 208, 30082.
  • Zeros at the start of decimal numbers are not significant, because they are only used to position a decimal point, eg. 0.02, 0.000805.
  • Zeros at the end are significant only if they are to the right of the decimal point, because they show accuracy, eg. 125.50 but not 2040.

Textbook page references

Self-study course

  • National5.com   Highly recommended. Save £10 with discount code 'Maths.scot'.

Examples

  • 208 has 3 significant figures
  • 30082 has 5 significant figures
  • 0.02 has 1 significant figure
  • 0.000805 has 3 significant figures
  • 125.50 has 5 significant figures
  • 2040 has 3 significant figures
  • 98.2 has 3 significant figures
  • 450 has 2 significant figures
  • 1.00023 has 6 significant figures
  • 0.999 has 3 significant figures
  • 9.99 has 3 significant figures

Rounding examples

  • 208 rounded to 2 sig. fig. is 210
  • 30082 rounded to 3 sig. fig. is 30100
  • 0.02 rounded to 1 sig. fig. is 0.02
  • 0.000805 rounded to 2 sig. fig. is 0.00081
  • 125.50 rounded to 2 sig. fig. is 130
  • 2040 rounded to 2 sig. fig. is 2000
  • 98.2 rounded to 1 sig. fig. is 100
  • 450 rounded to 1 sig. fig. is 500
  • 1.00023 rounded to 3 sig. fig. is 1.00
  • 0.999 rounded to 2 sig. fig. is 1.0
  • 9.99 rounded to 2 sig. fig. is 10. This may seem strange, because the number 10 only has 1 significant figure, but 9.99 rounded to 2 significant figures must be 10, because rounding it to 1 would be much too small.

Note

Past paper questions have also required candidates to round to a given number of decimal places, or to the nearest 10 or 1000. You should also ensure that you are able to do this.

Need a Nat 5 Maths tutor?

Just use this handy little widget and our partner Bark.com will help you find one.

Past paper questions

2014 P2 Q1 (nearest 10)
2014 Paper 2 Q7 (with volume)
2015 Paper 2 Q6 (with volume)
2016 Paper 2 Q7 (with volume)
2017 Specimen P2 Q6 (with volume)
2017 Paper 2 Q6 (with volume)
2018 Paper 2 Q7 (with volume)
2019 Paper 2 Q6 (with quadratics)
2019 Paper 2 Q8 (with volume)
2021 Paper 2 Q11 (with volume)
2021 Paper 2 Q15 (with quadratics)
2022 Paper 2 Q2 (nearest 1000)
2022 Paper 2 Q7 (with quadratics)
2023 P2 Q3 (with scientific notation)
2023 P2 Q14 (with quadratics)
• 2024 Paper 2 Q1 (with percentages)
• 2024 Paper 2 Q8 (with quadratics)

Other great resources

Video - Larbert High School
Notes - BBC Bitesize
Notes - Maths4Scotland
Videos - Mr Thomas Maths
Worked examples - Maths Mutt
Worksheet - Corbett Maths

⇦ Nat 5 topic list  ⇧ Top of this page