When we add or subtract integers we can use a number line to help us see what is happening with the numbers.

At the centre of the number line is the integer zero.

The positive numbers are to the right along the number line. When we add integers we move “up” in this direction.

The negative numbers are to the left along the number line. When we subtract integers we move “down” in this direction.

Example: = ?

Example: = ? Let’s start at the first integer in our sum, that is, positive one.

Example: = ? Let’s start at the first integer in our sum, that is, positive one.

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line).

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line).

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +1

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +2

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +2

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +2

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +3

Example: = ? Let’s start at the first integer in our sum, that is, positive one. We are going to add +3 so we need to move 3 places up (to the Right on our number line). +3 We end up at the value 4. So… = 4

Example: = 4

Example: = ?

Example: = ? We will start at +1 again as this is the first part of our sum

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line -2

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line -2

Example: = ? This time we are subtracting 3 so we will move “down” (to the left) on our number line -3

Example: = ? -3 We end up at negative two. So… 1 – 3 = -2

Example: = -2

What about: = ?

What about: = ? We will start at negative four on the number line

What about: = ? We are subtracting 3 so we will move “down” (to the left) on our number line by 3 units

What about: = ? We are subtracting 3 so we will move “down” (to the left) on our number line by 3 units

What about: = ?

What about: = ?

What about: = ?

What about: = ?

What about: = ?

What about: = ? We end up at negative seven, so…

What about: = -7

Finally, what do these mean? ? ?

Finally, what do these mean? ? ? A plus and minus together means the same as subtract. So replace them with a minus sign

Finally, what do these mean? is the same as ? A plus and minus together means the same as subtract. So replace them with a minus sign

Finally, what do these mean? is the same as ? Two minus signs together means the same as add. So replace them with a plus sign

Finally, what do these mean? is the same as is the same as 5 + 2