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This topic rounds numbers to a given number of decimal places or significant figures and uses rounding to estimate the result of a calculation. It's examined right across GCSE and iGCSE Maths. Work through it free on eClassroom, with clear worked examples and instantly-marked questions that build your confidence for the exam.
How you do it
Look at the digit after the one you are rounding to. Five or more rounds up, four or less rounds down. To estimate, round every number to one significant figure first, then do the calculation with the rounded values.
Before you start
Before starting, revisit place value and decimals. It then feeds into significant figures, bounds and checking answers.
What you learn
Rounding makes numbers simpler to handle, and estimating lets you check whether an answer is sensible — a skill examiners test directly. To round to a number of decimal places (dp), look at the next decimal digit and apply the same 5-or-more rule. To estimate, round each number to 1 significant figure, then do the easy calculation. The course works through rounding to the nearest 10, 100, 1000, rounding to decimal places and estimating calculations. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
We teach Rounding & Estimation as one of the Number topics in our GCSE course library, at Foundation tier. It runs to 3 concepts, each followed by a check, with 2 worked examples along the way. Related topics students usually take next include Significant Figures & Truncation, Standard Form, Standard Units & Measures and Surds. You can drill this strand further on the Number revision engine, with your accuracy saved to your skill tree.
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