Arithmetic Grade Five

Lesson One hundred and seventy-four: 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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