# Using a number line

A number line can be useful when answering questions involving negative numbers.

When adding a positive number, go up the number line (move to the right).

When subtracting a positive number, go down the number line (move to the left).

### Example

$6 - 3$

Start at $$6$$ and go down $$3$$.

Now try these questions and remember the number line!

Question

Calculate $$4 - 5$$

Start at $$4$$ and go down $$5$$.

The answer is $$-1$$.

Question

$- 2 + 5$

Start at $$-2$$ and go up $$5$$.

The answer is $$3$$.

Question

$4 - 9$

Start at $$4$$ and go down $$9$$.

The answer is $$-5$$.

Question

$3 - 10$

Start at $$3$$ and go down $$10$$.

The answer is $$- 7$$.

Question

$- 9 + 12$

Start at $$-9$$ and go up $$12$$.

The answer is $$3$$