Arithmetic Grade Six

Lesson One Hundred Sixty-one: Missing Numbers

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


        5 + __ = 12
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: 

       __ + 9 = 30
Using subtraction we can find the answer: 
 
     30 - 9 = __
Now you get to try a few of these yourself.

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