Significant figures are the digits in a number that contribute to the accuracy of the number. The first significant figure is the first non-zero digit.

To change a number into another number that is approximately the same value but is easier to work with. E.g. round 561 to the nearest 10 is 560.

Rounding decimals to significant figures

Maths

In this unit, pupils have learnt how to round to a given number of decimal places or significant figures and explored the effect of using rounded numbers for calculations. In the future unit, pupils will investigate the bounds and perform calculations to determine a best/worst case scenario.

The prior unit on place value allowed pupils to develop the skills needed to estimate and round values. By understanding the value of each digit, pupils can determine what other values are close to the original value. This unit continues the exploration of the infinite nature of sets of numbers.

Estimation and rounding

The first {{ }} figure is the first non-zero digit in a number.

Match each number to the correct statement.

In the number 56 072, the 7 is the {{ }} significant figure.

Select the numbers that have 3 as the third significant figure.

Select all the numbers which have zeros that are not needed to preserve the place value of other digits.

This lesson will soon be taken down.

Rounding decimals to significant figures

Lesson outcome