Eddie and Ellen use a calculator to work out 624.618.6+4.82\displaystyle \frac{624.6}{18.6 + 4.8^2}18.6+4.82624.6
Eddie's answer is 1.5
Ellen's answer is 15
One of those answers is correct.
Use approximations to find out which answer is correct and then verify your conclusion by working out the exact value.
247 exam-style questions on Eduqas GCSE Maths Estimating. Each one has a worked solution and a mark scheme showing where the marks go.