Estimation (Edexcel GCSE Maths): Flashcards

Method to find an approximate answer to a calculation

Approximately equal to

1 significant figure

$4 \times 20 = 80$

$300^2 = 90,000$

Multiply both numbers by same amount, answer stays same

$140,000 \div 5 = 28,000$

$4^3 \times 10^3 = 64 \times 1000 = 64,000$

Estimated answer smaller than true answer

Estimated answer larger than true answer

3

Round each number to 1 significant figure