GCSE · Rounding & bounds

EstimationExam-style questions

Why estimating means rounding everything to 1 significant figure BEFORE calculating, how to divide by decimals cleanly, and how to reason about whether an estimate is an over- or underestimate.

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15 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 1Level 2Level 3Level 4Level 5
  1. 1
    Work out an estimate for the value of 48.6×21.29.7\dfrac{48.6 \times 21.2}{9.7}

    You must show your working.
    Level 3 · 3 marksTry it
  2. 2
    Work out an estimate for the value of 19.6×5.3\sqrt{19.6 \times 5.3}

    You must show your working.
    Level 3 · 3 marksTry it
  3. 3
    Work out an estimate for the value of 39.2×5.19.8\dfrac{39.2 \times 5.1}{9.8}

    You must show your working.
    Level 3 · 2 marksTry it
  4. 4
    Work out an estimate for the value of 6.8×3.1×4.96.8 \times 3.1 \times 4.9

    You must show your working.
    Level 3 · 2 marksTry it
  5. 5
    Ivan orders 587587 metres of fencing wire.

    The wire costs 38.438.4p per metre.
    (a) Work out an estimate for the total cost of the wire.

    Give your answer in pounds.

    (3 marks)
    (b) Is your answer to part (a) an underestimate or an overestimate?

    Give a reason for your answer.

    (1 mark)
    Level 3 · 4 marksTry it