Arithmetic Grade Four

Lesson One hundred and seventy-eight: Parentheses

Parentheses can make a big difference in a problem. Consider these two examples: 


        5 * 5 + 5 = 30

        5 * (5 + 5) = 50
In the first case we multiply 5 time 5 and then add 5. In the second case we add 5 + 5 and then multiply this sum by 5. The rule is that we always do the operations inside parentheses before the other operations. Otherwise, you will recall that multiplication and division come before addition and subtraction.

Here's another example: 

 
     6 + 7 * 8 = 62

     (6 + 7) * 8 = 104
Now you get to try a few of these yourself.

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