Unit 3 Contents

Grouping and Ordering

To find the number of apples in the crate, David, Arti, and Lin multiplied 3 4 5 three different ways.

David multiplied 3 4 first.       Arti multiplied 4 5 first.       Lin multiplied 3 5 first.

2. Mrs. Dewey asked her class to multiply 2 4 6.
   Jackie wrote this number sentence:
   
   Luis wrote this number sentence:
   
   1. What is the same about these two sentences?
   2. What is different about these two sentences?
   3. How are the middle parts different?
   4. What do you think the circles might be telling you?
   5. Does multiplying different numbers first change this answer?
   6. Does it matter what numbers you multiply first for other number sentences? Try it with 2 3 6.
   7. Is the same thing true for any number sentence with three numbers being multiplied?

Jackie and Luis showed what they multiplied first by circling the factors. Mathematicians use parentheses to group factors and show which factors to multiply first. For example, Jackie's and Luis's number sentences can be written with parentheses like this.

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