Approximation and Estimation

Chapter 3 Study Notes

Section 1 of 7

Learning Outcomes

  • Understand the difference between approximation and estimation
  • Round off numbers to a given number of decimal places
  • Identify significant figures using the 5 rules
  • Round off numbers to a given number of significant figures
  • Estimate computations by rounding to 1 significant figure
  • Apply estimation in real-world contexts (currency, value for money, sampling)
Contents

Why Approximation and Estimation Matter

In June 2025 Singapore’s population was 61112006\,111\,200, and the news said "6.11 million". The rounded figure is easier to hold and still true enough.

Practise this

Questions on Approximation and Estimation, marked as you go, with the working shown.

Practise Approximation and Estimation