Let’s Learn!
What is Multiplication?
Goal:
Goal:
Think About It!
Goal: Use pictures, skip counting, number lines and repeated addition to multiply.
How many pencils do you see? We can use multiplication to find out!
To use multiplication to find the number of pencils, we need to know how many groups of pencils there are, and how many pencils there are in each group. These two numbers are called factors. When we multiply, we always start with the first factor which is the number of groups. In our picture, the 4 desks are the number of groups. We multiply the number of groups by the second factor, which is the number in each group. In our picture, the 5 pencils on each desk are the number in each group. So, our factors are 4 and 5.
We can say that we have 4 groups of 5 pencils. We can create a multiplication sentence to show this problem. A multiplication sentence has the first factor, a multiplication symbol, the second factor, an equal sign, and a product. The product is the answer when we multiply our 2 factors. Click on the multiplication sentence to see all of the parts!
factor
number of groups
factor
number in each group
product
total number
Here is the multiplication sentence we will use to find the number of pencils on the desks.
How do you find the product? Here are some strategies that you can use. Each strategy is like a tool in a toolbox.
Let’s look at how we can use each strategy to find out how many pencils there are!
4 groups of 5 = 20
Click image to enlarge
Repeated Addition
Repeated addition is adding the same number over and over. The number of groups tells us the number of addends. There are 4 desks, so we have 4 addends. The number of pencils on each desk is the number in each group. There are 5 pencils on each desk, so each addend will be 5. The sum is the total, which is called the product when we multiply. We have 4 groups of 5. We need to add 5 four times to find the product: 5 + 5 + 5 + 5 = 20.
4 groups of 5 = 20
Click image to enlarge
Skip Counting
Skip counting is counting up or down by the same number. We have 4 groups of 5. We need to skip count by 5 four times to find the product: 5, 10, 15, 20.
4 groups of 5 = 20
4 groups of 5 = 20
4 \({ \times }\) 5 = 20
4 \({ \times }\) 5 = 20
Click images to enlarge
Multiplication Picture
The multiplication picture above uses pictures to show each factor. The first factor—the number of groups or desks —is shown by big, red circles. The second factor —the number of pencils in each group —is shown by the small, yellow circles. This picture shows 4 groups of 5! That is 4 \({ \times }\) 5. To get the product, we need to count the dots or skip count.
4 \({ \times }\) 5 = 20
Click image to enlarge
Number Line
We can use a number line to skip count. When we add, we skip count to the right. The product is the number you land on. We have 4 groups of 5. We need to jump 5 numbers 4 times to find the product.
Since 4 \({ \times }\) 5 = 20, there are 20 pencils!