Make Arrays to Find Totals

Key Concepts

• Find the totals by using an array

Introduction 

Write whether the given image is an array or not. Find the number of rows and columns present in the image. 

Yes, the given image is an array because the number of rows and columns are equal. 

There are 2 rows and 5 columns. Each row contains 5 trees, and each column contains 2 trees. 

Repeated addition: 

We can model repeated addition with an array. 

3 + 3 + 3 + 3 = 12

Here, we are adding 3 stars four times. 

Example: 

Model repeated addition with an array. 

Here, we can add 4 smileys repeatedly.  

4 + 4 + 4 + 4 = 16 

Arrays

We can define an array as a set that shows equal groups in rows and columns. 

Here, we can see that there are three rows and four columns. 

Example: 

Write whether the image given below is an array or not. 

Here 4 rows and 3 columns are present in the image. 

Add the number of tortoises in each row. 

Here there are 4 rows, and each row contains 3 tortoises. 

So, the equation for the row is, 

3 + 3 + 3 + 3 = 12 

Add the number of tortoises in each column. 

Here there are 4 columns, and each column contains 3 tortoises. 

So, the equation for the column is, 

4 + 4 + 4 = 12 

Example: 

Count the number of rows and columns present in the given image and write the equation for both. 

Solution:  

Add the number of objects in each row. 

Here there are 3 rows, and each row contains 3 shells. 

So, the equation for the row is, 

3 + 3 + 3 = 9 

Add the number of objects in each column. 

Here there are 3 columns, and each column contains 3 shells. 

So, the equation for the column is, 

3 + 3 + 3 = 9 

Example: 

Write the number of rows and columns the given image has. 

Solution: 

There are 4 columns and 3 rows. 

Each column has 3 objects, and each row has 4 objects. 

Example: 

Write two equations that explain the array. 

Solution: 

By rows, the required equation is 4 + 4 = 8 

By columns, the required equation is 2 + 2 + 2 + 2 = 8. 

So, the required answer is 5 + 5.

Exercise

• Write two equations that represent the array.

• Write the equation by rows for the array.

• Write the equation by rows for the array.

• Write the equation by rows for the array.

• Write the equation by columns for the array.

• Write the equation by rows for the array.

• Write two equations that explain the array.

• Write the equation by columns for the array.

• Write two equations that explain the array.

• Write the equation by columns for the array.

Concept Map

What we have learned

• How to find the total by using an array?