Mathematics for IGCSE & O level - Estimation (Section 3 - No. 46)

What are the steps to estimate the result of a calculation, rounding to 1 significant figure?

Round each number to the nearest whole number, then perform the calculation.

Round each number to 1 significant figure, then perform the calculation.

Use a calculator and record all the digits displayed.

Round each number to 2 significant figures and perform the calculation.

To estimate, round all the numbers involved to 1 significant figure, then perform the calculations.