# Four operations using positive and negative integers

Students are required to be fluent when required to add, subtract, multiply and divide combinations of positive and negative integers. This resource list supports the teaching and learning of the use of the four operations, including efficient written methods, applied to integers both positive and negative.

Visit the secondary mathematics webpage to access all lists.

### Directed Numbers

This resource contains games, investigations, worksheets and practical activities. The common theme in these activities is the importance of using a number line when dealing with directed numbers.

**Snakes and adders** is a dice game for two players requiring students to add and subtract directed numbers.

**Adding shifts **adds** **and subtracts directed numbers on a number line.

**Adding directed numbers** uses a number line.

**Subtracting directed numbers** uses diagrammatic representations on a number line.

### Calculations with negative numbers

This resource explains how to use a number line when performing calculations when the starting point is a negative value. Phrases such as owing and debt are used to help students deal with directed number in context.

Further practice of using directed numbers is provided by follow-up exercises.

### Directed Numbers Mystery

This activity requires students to think about the mathematics and the strategy required to solve the given problems. Students have thirteen cards, each with a statement about directed numbers, and clues as to where the card should be placed on a 3 by 3 answer grid. The rationale is that students discuss possible options of which directed number lies in each of the cells.

A blank 3 by 3 grid is available as a separate file and it is recommended to enlarge this to A3 size.

### Using Directed Numbers in Context N8

This resource uses the context of temperatures as a vehicle for students to use directed numbers. Students are provided with the temperatures in four cities, temperature differences between these and four other cities are also given. Students are asked to find missing temperatures and temperature differences. This leads students to consider one interpretation of addition and subtraction using negative numbers.

### Evaluating Directed Number Statements N9

Students are required to make valid generalisations about the effect of operations on directed numbers. It is helpful if students have already attempted to use directed quantities in contexts before attempting this session. Students are provided with a collection of statements and have to decide whether each statement is always, sometimes or never true. To test understanding, students are required to justify their choices using examples and counter-examples.

### Arithmetic: Negative Numbers

**Arithmetic: negative numbers** contains a variety of examples and exercises providing practice and consolidates material in addition, subtraction, multiplication and division of directed numbers.

The activity **Human Number Line** is a practical activity in which students use a human number line to add and subtract directed numbers.

**Multiplication and Division** is an activity which requires students to investigate what happens when directed numbers are multiplied and divided.

### Positive and Negative Numbers - Brick Walls

This excel file gives unlimited practice questions on the four operations with positive and negative numbers- by asking students to complete missing vales in 'brick wall' exercises.