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Rounding and estimation

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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.

By: The Open University

  • Duration 5 hours
  • Updated Monday 1st September 2014
  • Introductory level
  • Posted under Mathematics Education
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Rounding and estimation


Unit image

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 subject area [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .

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