## What you need to know

Things to remember:

• Adding a positive number is like taking away the negative from the positive.
• If we are taking away a big number from a small number, swap them around and put a minus on the answer.

Intervals across 0 just means adding and subtracting so that the numbers swap between positive and negative.

$$3-8$$

$$12-16$$

$$-4+8$$

$$-2+12$$

We all know how to add, it is just counting up.

What is $1+4$?

So here, we’re starting at 1 and counting up 4 times.

So, $1+4=5$!

We do this in the same way when adding a positive number to a negative number.

What is $-1+4$?

We started at -1 and counted up 4 to get 3, so $-1+4=3$. But, we also know that $4-1=3$. So, we can change the numbers and make it into a subtraction question!

$$-5+12=12-5=7$$

$$-3+9=9-3=6$$

$$-10+15=15-10=5$$

How about if we take a big number away from a small number? What is $4-6$?

So, $4-6=-2$. It is important to notice that $6-4=2$. But why is this important? Let’s put them together to see

$$4-6=-2$$

$$6-4=2$$

If we swap the numbers we are subtracting, we can see that the answer goes from negative to positive. So, when subtracting a big number from a small number, we can swap them around and just put a negative on the answer!

What is $9-15$?

$$15-9=6$$

$$9-15=-6$$

## Example Questions

#### Question 1: What is $-5+8$?

$$-5+8=8-5=3$$
#### Question 2: What is $7-19$?
$$19-7=12$$
$$7-19=-12$$