Derek explains Section D and how it is broken into another seven chapters, explaining everything else about number and calculations that might be found in a primary school curriculum. This includes proportionality and square numbers. He states that the priority here is to develop the feel for numbers, offering an example of this by referring to ‘12’ as a friendly number because it is a composite number that can be arranged into equal numbers while ‘11’ cannot be. Derek argues that explorations such as this can develop a fascination with numbers. He expands upon this by using visual patterns made with link cubes creating ‘L’ shapes that help visualize odd numbers and how they can create square numbers. The relationships and patterns between numbers are key here.

Derek then outlines other more routine areas that this section looks at including numerical situations such as handling decimals. The importance of this is explained when Derek links the importance of handling decimals with the context of measuring and other practical situations.  He argues that some of the information is high level, giving the example of understanding percentage increase as a way for teachers to express relationships and comparisons in everyday life. Derek shares that his aim for this section is to inspire more confidence in numerical situations relevant to a primary school teacher.