N15a – Rounding and truncating

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Prerequisites
  • An understanding of place value is required.

Skill isolation: rounding to the nearest \(x\)

This applet allows you to generate questions on rounding, and to reveal step-by-step solutions using the slider. The steps involved are:

  1. Finding relevant consecutive multiples.
  2. Finding the midpoint of the consecutive multiples.
  3. Identifying where a number lies on a given section of the number line.
  4. Deciding what a given number rounds to.

Each of these skills can be practised in isolation by dragging the slider to the appropriate level and then clicking on one of the bullet points towards the top-right to generate another question isolating the same skill.

Part 1 – Rounding to a given place

Teacher resources for Part 1

Teachers: log in to access the following:

  • Slides in PPTX (with click-to-reveal answers)
  • Slides in PDF (one slide per page, suitable for importing into IWB software)
  • Desmos classroom activity: Rounding to a given place value (20 randomised questions) Find out more
Links to past exam questions

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Part 2 – Rounding to a given number of significant figures

Teacher resources for Part 2

Teachers: log in to access the following:

  • Slides in PPTX (with click-to-reveal answers)
  • Slides in PDF (one slide per page, suitable for importing into IWB software)
  • Desmos classroom activity: Rounding to a given number of significant figures (20 randomised questions) Find out more
Links to past exam questions

Teachers: log in to access these.

Part 3 – Truncating decimals

This topic consists only of an examples slide (with embedded video) and a random question generator below.

Links to past exam questions

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Cross-curricular link: climate change


This is based on data from https://www.globalwarmingindex.org

  1. Round the temperature change figure to two decimal places.
  2. Round the temperature change figure to two significant places.
  3. Truncate temperature change figure to two decimal places.

In the real world

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