Revision Notes

Why use estimation?

We ESTIMATE to find approximations for difficult sums or to check our answers are about the right size (right order of magnitude).

How to estimate

We ROUND numbers to something sensible before CALCULATING.

    Round numbers to 1 significant figure 

    • 7.88
    • 1820
    • 3.65 × 10-44 × 10-4
    • 10801000
    It can be more sensible (or easier) to round to something convenient

    • 16.215
    • 9.110
    • 11801200
    • It wouldn’t usually make sense to round a number to zero
  3. FRACTIONS get bigger when the top is bigger and/or the bottom is smaller and vice versa


Rounding & Estimation, IGCSE & GCSE Maths revision notes


Edexcel GCSE Maths Notes

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