Starting at 0 we can count up in units like this:
0 1 2 3 4 5 6 7 …
But what happens before zero?
We have the negative numbers, like this:
-7 -6 -5 -4 -3 -2 -1 0
If we count up, we move from the left to the right and the numbers increase.
So, -7 to -6 is moving from the left to the right and the numbers have increased because -6 is bigger than -7.
If we count back, we move from the right to the left and the numbers decrease.
So, -3 to -4 is moving from the right to the left and the numbers have decreased because -4 is smaller than -3.
Here is part of a number line going from 7 down to -7:
-7 – 6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Example
Count back to work out the missing number.
-4 -3 -1 0 1 2 3
What is the missing number?
Answer
Counting back from 0 means the numbers decrease.
-3 -2 -1 0
So the missing number is -2.
