Work Out the Missing Number in a Variety of Calculations

In this activity, we will work out missing numbers in calculations.

Example 1

Find the missing number.

26 + ? = 50

Here, it is easy to work out the inverse.

50 - 26 = 24

Example 2

Find the missing number.

-26 + ? = 50

Here, we use the inverse again, but be careful about the negative sign.  

Two negatives next to each other means a positive.

50 - -26 = 50 + 26 = 76

In this activity, we will be using inverse operations to find the missing numbers.