Subtraction as difference
Difference is a comparison between two or more sets.
For example, if a set of 8 is compared with a set of 5, there is a difference of 3 objects between the sets.
This may be recorded as 5 + 3 = 8 or 8 – 5 = 3 where 3 is the difference.
In mental calculation it is often easier to regard a take away subtraction context as finding a difference. Adding on to solve the problem is frequently easier.
For example, 203 – 188 = ? is easier to solve as 188 + ? = 203.
Finding difference is contextually more difficult than taking away as the situation does not suggest a physical action to solve it.
You can read more about inverse operations.
Finding the difference between two quantities is a common type of calculation. Difference problems can be solved using either subtraction or adding on from the smaller number.
Difference problems can be made easier by adjusting both numbers by the same amount.