Truncation is the simplifying a number by 'cutting off' one or more of the digits and replacing them with zeros if necessary to preserve place value.

A degree of accuracy shows how precise a number or measurement is.

Truncating

Maths

Checking understanding of rounding

Securing understanding of rounding

Rounding to three decimal places

Rounding to any number of decimal places

Rounding integers to one significant figure

Rounding integers to significant figures

Rounding decimals to significant figures

Degrees of accuracy

Estimating numerical calculations

Checking by estimating

Overestimating vs underestimating

Rounding errors

Inequality notation to express error

Using inequality notation for errors in calculations

Problem solving with estimation and rounding

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.

This unit helps pupils understand rounding to different decimal places, and significant figures. Pupils will also learn how to truncate numbers and understand the contexts in which these skills are useful. The unit ends will an exploration of rounding and inequality errors.

Estimation and rounding

__________ is the simplifying a number by 'cutting off' one or more of the digits and replacing them with zeros if necessary to preserve place value.

Match each number with its truncated value to 1 significant figure.

Truncate 49.999999 to 3 significant figures. Select the correct response.

Jacob thinks of a number. Truncated to 1 s.f. Jun's number is 100. Jun's number is a multiple of 8 and it is 105 when rounded to the nearest 5.

A length of wood 37 m needs to be cut into 5 equal strips.

A meal is £37 and you share it between 5 people and want to give a tip

You have £37 and want to buy as many £5 puzzle cubes as possible. 

Match the appropriate treatment of the answer (exact, rounded to truncated) to each context.

In computer science, ‘INT’ or ‘int’ is used to truncate a number so to only give the integers. For example, INT(56/10) has an output of 5. Match each computer instruction to its output.

__________ shows how precise a number or measurement is.

A square plot of grass has a length of 2.89 m to 2 decimal places. Select the correct estimate for the area of the square grass plot.

Which of the following are correct, quick estimate calculations for $${4.56\times8.95} \over {0.498}$$?

Match each calculation to its correct approximate answer. 

Truncating

Lesson outcome