Addition and Subtraction Fact Families
You can turn around the numbers being added (the addends) and you will still have the same total.
If you know that 12+3= 15
then you know that 3+ 12= 15
Addition and subtraction are linked:
This is what we call a Fact Family.
Here is another;
It is important to notice that these subtraction facts begin with the largest number.
Now you could try making up some fact families of your own.