from The Open University
Alternatively you can skip the navigation by pressing 'Enter'.
Life: InsectsTuesday, 9th February 2016 05:00 - Eden EdenYou think there's a lot of people? There's a lot more insects. Read more: Life: Insects
The London Markets: The Fruit And Veg Market: Inside New SpitafieldsAvailable until Sunday, 13th March 2016 00:40The fruit and veg trade in England was once a closed world dominated by traditional British costermonger families.... Read more: The London Markets: The Fruit And Veg Market: Inside New Spitafields
Thinking Allowed 2016: Consumerism, Work-life balanceAvailable for over a year
More or Less: E-cigs, politics, school and birthdaysAvailable for over a year
The Bottom Line: Winter 2015-16: Renewable EnergyAvailable for over a year
The Open University at 45: What can we learn from Britain's distance educatio...This month sees the 50th anniversary of the government ‘White Paper’ which launched the OU in... Read more: The Open University at 45: What can we learn from Britain's distance education pioneer?
OpenLearn Live: 9th February 2016The king who saw a tree bend and embraced peace and the day when pancakes are centre stage. Free... Read more: OpenLearn Live: 9th February 2016
Discovering Wales and Welsh: first stepsThis free course, Discovering Wales and Welsh, introduces you to who the Welsh people are via a... Try: Discovering Wales and Welsh: first steps now
Start writing fictionHave you always wanted to write, but never quite had the courage to start? This free course,... Try: Start writing fiction now
Scientific calculators are a wonderful invention, but theyre only as good as the people who use them. If you often get an unexpected or ridiculous result when you press the enter button, this free course, Rounding and estimation, is for you. Learn how to do a calculation correctly and get the right answer every time.
By the end of this free course you should be able to:
- round a given whole number to the nearest 10, 100, 1000 and so on;
- round a decimal number to a given number of decimal places or significant figures;
- use rounded numbers to find rough estimates for calculations;
- use a calculator for decimal calculations involving +, −, × and ÷, giving your answer to a specified accuracy (e.g. decimal places or significant figures) and checking your answer by finding a rough estimate;
- check your answers to calculations by ensuring that the correct calculation has been done, in the correct order;
- check your answers by checking that the units are consistent;
- check your answers by checking the result against a rough estimate;
- check your answers by checking that the answer makes sense in the context of the problem.
- Current section: Introduction
- Learning outcomes
- 1 Rounding
- 1.1 Rounding in daily life
- 1.2 Rounding whole numbers
- 1.3 Rounding in general
- 1.4 Rounding decimals
- 1.5 Significant figures
- 1.6 Significant figures for numbers less than one
- 2 Estimation
- 3 Checking your answers
- 3.1 Have I done the right calculation?
- 3.2 Have I used the correct order for my calculation?
- 3.3 Have I given due consideration to units of measurement?
- 3.4 Did I make a rough estimate to act as a check?
- 3.5 Does the answer make sense in the real world?
- 3.6 Additional practice
- 4 OpenMark quiz
- Keep on learning
Study this free course
Enrol to access the full course, get recognition for the skills you learn, track your progress and on completion gain a statement of participation to demonstrate your learning to others. Make your learning visible!
Rounding and estimation
For many calculations you use a calculator. The main aim of this unit is to help you to do this in a sensible and fruitful way. Using a calculation to solve a problem involves four main stages:
Stage 1: working out what calculation you want to do;
Stage 2: working out roughly what size of answer to expect from your calculation;
Stage 3: carrying out the calculation;
Stage 4: interpreting the answer – Does it agree with the rough estimate? Does it make sense in terms of the original problem?
This unit focuses on Stages 2 and 4.
This unit is from our archive and is an adapted extract from Open mathematics (MU120) which is no longer taught by The Open University. If you want to study formally with us, you may wish to explore other courses we offer in.
This free course includes adapted extracts from an Open University course which is no longer available to new students. If you found this interesting you could explore more free Mathematics Education courses or view the range of currently available OU Mathematics Education courses.
Copyright & revisions
Originally published: Friday, 10th June 2011
Last updated on: Monday, 1st September 2014
- Creative-Commons: The Open University is proud to release this free course under a Creative Commons licence. However, any third-party materials featured within it are used with permission and are not ours to give away. These materials are not subject to the Creative Commons licence. See terms and conditions. Full details can be found in the Acknowledgements and our FAQs section.
- This site has Copy Reuse Tracking enabled - see our FAQs for more information.
If you enjoyed this, why not follow a feed to find out when we have new things like it? Choose an RSS feed from the list below. (Don't know what to do with RSS feeds?)
Remember, you can also make your own, personal feed by combining tags from around OpenLearn.
All our alternative formats are free for you to download, for more information about the different formats we offer please see our FAQs. The most frequently used are Word (for accessibility), PDF (for print) and ePub and Kindle to download to eReaders*.
*Please note you will need an ePub and Mobi reader for these formats.