Use of array

Key Concepts

• Use of array for finding product
• Use of area model for finding product

What is an array? 

An arrangement of objects, pictures, or numbers in rows and columns is called an array. 

Arrays are really helpful if you want to think of splitting the multiplicand instead of the multiplier. 

The below image is an example of an array model for multiplication. 

What is an area model? 

An area model is a rectangular diagram or model used for multiplication. 

4. 2.1 Use of array for finding product           

Joe moving company has boxes for packing biscuit packets. If each box holds 16 packets, how many packets would fit into 10 boxes? 

Solution: 

Step1: Use place value blocks to make an array. 

Find 10 x 16. 

Step2: Draw array for 10 x 16.  

Step3: Then multiply 10 x 10 = 100,   10 x 6 = 60. 

Step4: Add 100 + 60. 

10 x 16 = 160 

160 packets fit in 10 boxes.  

Example2: 

Find the product of 10 x 13. Solve this problem using the array strategy. 

Solution:   

Step1: Use place value blocks to make an array. 

       Find 10 x 13 

Step2: Draw array for 10 x 13. 

Step3: Then multiply 10 x 10=100, 10 x 3 =30. 

Step4: Add 100+ 30. 

4.2.2 Use of area model for finding product  

Draw an area model to show 10 x 23. Then find the product.       

Solution:  

Step1: Draw a rectangle for the area model. 

Step2: Multiply 10 x 20 and 10 x 3. 

10 x 20 = 200 

10 x 3 = 30 

Step3: Now add two partial products. 

10 x 23 = 230. 

Example2: 

Draw an area model to show 20 x 48. Then find the product. 

Solution:  

Step1: Draw a rectangle for the area model. 

              Multiply 20 x 40 and 20 x 8. 

Multiply 20 x 40 and 20 x 8. 

Step3: Now add two partial products. 

Exercise:

1. The place value block array shows 10 x 14. Find the product.

2. The place value block array shows 10 x 17. Find the product.

3. Find the product of 10 x 17.

4. Draw an area model to show 30 x 48. Then find the product.

5. Use an area model to find the product of 40 x 57.

6. Find the product of the given area model.

7. Find the product of 80 x 37 using an s area model.

8. Draw an area model to show 60 x 76. Then find the product.

9. Find the product of 50 x 56 using partial product model.

10. Use place value block, area models, or arrays to find each product.
20 x 48
30 x 29

Concept map:

What have we learned:

• Understand an array.
• Understand how to use place value blocks to make an array.
• Understand how to use array model for finding product.
• Understand how to use area model strategy for finding product.
• Identify the partial products.