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PRACTICE: Multiplication and Division

Lesson

Practice

Let's go over some of the multiplication and division strategies and problems we've looked at. These include:

  • using arrays and area models
  • partitioning numbers by place value
  • using a standard algorithm

We also looked at using a standard algorithm to solve multiplication or division, for larger numbers. This strategy is useful if we need to trade, or regroup.

Apply

QUESTION 1

Let's use the area model to find $29\times28$29×28.

  1. Fill in the areas of each rectangle.

                $20$20               $9$9
    $20$20           $\editable{}$               $\editable{}$    
                               
    $8$8           $\editable{}$               $\editable{}$    
                               
  2. Find the sums of each column

                $20$20               $9$9
    $20$20           $400$400               $180$180    
                               
    $8$8           $160$160               $72$72    
                               
    Total:           $\editable{}$               $\editable{}$    
                               
  3. What is the total area of the rectangles?

                $20$20               $9$9    
    $28$28           $560$560               $252$252    
     
     
     
  4. So what is $29\times28$29×28?

QUESTION 2

Find the value of $651\div7$651÷​7.

QUESTION 3

Find the value of $297\div16$297÷​16.

  1. $\editable{}$ with remainder $\editable{}$

Remember!

Arrays and the area model are great to solve multiplication or division problems when there will be no remainder. If we are not sure, we can use a standard algorithm.

Outcomes

5.NBT.B.5

Fluently multiply multi-digit whole numbers (up to three-digit by four-digit factors) using efficient strategies and algorithms.

5.NBT.B.6

Find whole-number quotients and remainders of whole numbers with up to four-digit dividends and two-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

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