In this worksheet you must find the missing number in a sum.
Example
Find the number that makes the sum correct.
332 + __ = 900
Answer
The opposite (inverse) of adding is subtracting.
So we work out 900 - 332 = 568
Here is a simpler example:
400 + ___ = 600
The inverse operation is
600 - 400 = 200
The answer is 200