Rounding & Estimation

Round accurately to decimal places and significant figures, then use convenient values to estimate calculations.

Curriculum rangeYears 5–11

Whole part

1st decimal

2nd decimal

3rd decimal

Round to

4.726

Look at the digit just after the 1st decimal place-- here it's 2. Less than 5, so round down (keep it the same).

≈ 4.7

Learning notes

Rounding & Estimation essentials

Keep these rules beside you while you explore and practise.

Locate the required decimal place, then use the next digit to decide whether it changes.

Begin counting at the first non-zero digit. Placeholder zeros may still be needed in the rounded answer.

0,1,2,3,4:\text{ keep}\qquad5,6,7,8,9:\text{ round up}

Round each value to one significant figure or another convenient accuracy, then calculate mentally.

\dfrac{19.8\times3.1}{0.49}\approx\dfrac{20\times3}{0.5}=120

💡Use ≈: a rounded or estimated value is approximately equal to the original, not exactly equal.