Arithmetic Grade Five

Lesson One hundred and seventy-seven: Parentheses and Missing Numbers

Consider the following two problems: 


        __ * 5 + 5 = 50

        __ * (5 + 5) = 50
What numbers complete these number sentences? 

	__ * 5 + 5 = 50

	MISSING NUMBER: 9
 


	___ * (5 + 5) = 50

	MISSING NUMBER: 5
The only difference between the two statements is the addition of parentheses in the second statement. But the parentheses make a big difference when it comes to figuring out what the missing number is.

Here's another example: 

 
     6 + __ * 7 = 20

     MISSING NUMBER: 2

     (6 + __) * 7 = 63

     MISSING NUMBER: 3
Now you get to try a few of these yourself.

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