Arithmetic Grade Six

Lesson One Hundred Sixty-one: Missing Numbers

Finding missing numbers in subtraction problems is really easy. Take a look at this problem. 


        12 - __ = 5
You probably almost instantly realized that the missing number was seven, but if you had difficulty finding the missing number you could use subtraction: 
 
     12 - 5 = __
Here's another example: 

        __ - 5 = 30
If the first number in a subtraction problem is missing, we can use addition to find the missing number. 
 
     30 + 5 = __
Now you get to try a few of these yourself.

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