Mathematics for IGCSE & O level - Using A Calculator (Section 1 - No. 23)
What could you use to estimate the answer when it is not exact?
Find an exact value.
Find a value to a given number of significant figures.
Work out the answer with a calculator.
Use the same method of estimating an answer as a check
Paliwanag
The best way to check your answer is by estimating your answer