Let’s Learn!
How can we use repeated addition to multiply?
Goal:
Goal:
Think About It!
Goal: Define repeated addition and how it relates to multiplication.
Look at these hands and try to count the fingers. How many fingers are there? We can use repeated addition to find out!
Repeated addition is adding the same number over and over. We can use repeated addition because each hand has the same number of fingers. Each hand in our picture has 5 fingers. 5 is the addend. Addends are the numbers we add together. The number we add over and over is the repeated addend. In our picture, there are 3 hands. 3 tells us how many times we add our repeated addend of 5. The answer is the sum.
_______ + _______ + _______ = _______
Take a look at the repeated addition sentence below. Click on the addends.
3
😃 This is an addend!
3
😃 This is an addend!
3
😃 This is an addend!
9
🤔 This is the sum.
It is easy to add when there are only 3 addends. What if there were 9 addends? It would take a long time to add them together. We can use repeated addition to help us multiply!
When we multiply, we take the number of groups times the number in each group to give us the total. We can also say we multiply a factor times a factor to get the product. The first factor tells us the number of groups. The second factor tells us how many are in each group. The product is the total of the number of groups times the number in each group. Let’s look at how repeated addition relates to multiplication.
Click image to enlarge
When we add using repeated addition, we add the same addend over and over, which gives us the total. To relate this to multiplication, the number of hands is the number of addends. The number of addends is the number of groups, which is the first factor. The repeated addend tells us the number in each group, which is the second factor. The total is the sum, which is the product.
Click below to find out how many fingers there are!
Let’s make a multiplication picture. It will help us see how many groups there are and how many are in each group!
There are 3 hands.
We can show each hand with one red circle.
Each hand has 5 fingers.
Each finger is shown by a blue dot in each circle.
Now we can write a repeated addition sentence. Repeated addition is adding the same number, or addend, over and over. First, we need to find the number of repeated addends. The repeated addend is the number we add over and over.
Let’s look at our drawing and count the number of red circles. The 3 red circles represent the 3 hands.
We can put a line under each circle. This tells us how many times the addend will be repeated.
_____ _____ _____
Each red circle has 5 blue circles for the 5 fingers on each hand. 5 is the repeated addend. We can put a 5 on each line.
5 _____ 5 _____ 5 _____
Now we can make our repeated addition sentence. The sentence needs plus signs between each addend, and an equal sign after the addends.
5 _____ + 5 _____ + 5 _____ = ?
We can use our repeated addition sentence to write a multiplication sentence.
5 + 5 + 5 = ?
The number of addends, or the number of red circles, is the first factor. The repeated addend, or the number of small blue circles, is the second factor. The sentence needs a multiplication sign (x) between the factors. It needs an equal sign after the factors.
Factors: the numbers we multiply together.
There are 3 addends. 3 is the first factor. 5 is the repeated addend. 5 is the second factor.
We can add or multiply to find the answer. Use the math sentence that works for you!
Product: the answer when we multiply
5 + 5 + 5 = 15
3 \({ \times }\) 5 = 15
5 + 5 + 5 = 15. 3 \({ \times }\) 5 = 15. There are 15 fingers on the three handprints!
Repeated addition helps us multiply. We found out that 3 \({ \times }\) 5 = 15 by adding three 5s. There are 15 fingers!