In this activity, you will be asked to find the missing number in a subtraction question.
The key to this activity is calculating every answer mentally (in your head) without using pen and paper.
Example 1
In your head, find the missing number
- 14 = 24
Answer
Use the inverse operation (addition) in order to find the answer:
14 + 24 = 38
Check
38 - 14 = 24
Example 2
- 0.6 = 2
Answer
Use the inverse operation in order to find the answer:
2 + 0.6 = 2.6
Check
2.6 - 0.6 = 2
Example 3
34 - = 11
Answer
Use the numbers you have been given to complete a subtraction sum in order to find the missing number:
34 - 11 = 23
Check
34 - 23 = 11
This method will make more sense when you attempt to answer some questions.