Step 4 Objective

Extend written methods to column addition and subtraction of numbers involving decimals.

Examples of what pupils should know and be able to do

Working with numbers to two decimal places, including:

Probing questions

Make up an example of an addition/subtraction involving decimals that you would do in your head and one you would do on paper. Explain why.

Give pupils some completed questions to mark. All questions need to be written horizontally as well as in column form. Include incorrect answers such as 12.3 + 9.8 = 21.11; 4.07 − 1.5 = 3.92; 3.2 − 1.18 = 2.18. Which are correct/incorrect? How do you know? Explain what has been done wrong and correct the answers.

What if pupils find this a barrier?

Ask pupils to bring in some old receipts, tear off the total part and pass the receipt to the pupil beside them to find the total. Can they do it on the receipt or do they need to lay it out differently?

For guidance on addition and subtraction with decimal notation refer to the document 'The National Numeracy Strategy: Teaching written calculations – guidance for teachers at Key Stages 1 and 2' (QCA/99/486) pp. 35–36.