Multiplication as Repeated Addition

Contributor: Erika Wargo. Lesson ID: 12391

Do multiplication problems add up to headaches for you? There's an easy way to tackle multiplication problems using pictures and plus signs. Play some games as you add this lesson to your math tricks!

categories

Elementary

subject
Math
learning style
Visual
personality style
Otter
Grade Level
Intermediate (3-5)
Lesson Type
Quick Query

Lesson Plan - Get It!

Audio:

You have volunteered to help the librarian move some books from the basement to the shelves. If there are 5 books in each box and there are four boxes, how many total books are there?

Addition is solving for the total number, or the sum.

An addition problem such as 4 + 4 + 4 would give us a total of 12. Multiplication is another way to find the total amount. Multiplication problems can be written as repeated addition problems. Multiplication means that you have a certain number of groups of the same size.

Now, you will learn more about repeated addition and multiplication. As you watch the Icon Math video, Multiplication and Repeated Addition, answer these questions on a piece of paper:

  • What does a multiplication sign look like?
  • What are factors?
  • Can 4 + 5 + 6 be written as a multiplication number sentence? Why or why not?

Discuss the questions above with a parent or teacher.

 

Example 1

Change this addition problem to a multiplication problem: 8 + 8 + 8 + 8 + 8 + 8

How many 8s do you see? There are six 8s, so the multiplication problem is 6 x 8.

Example 2

Which addition expression represents 3 x 5?

  1. 3 + 3 + 3
  2. 5 + 5 + 5
  3. 3 + 5 + 3 + 5

The expression 3 x 5 can be written as:

  • the number 3 written five times (3 + 3 + 3 + 3 + 3 = 15)
  • the number 5 written three times (5 + 5 + 5 = 15)

Answer b. 5 + 5 + 5 would best represent 3 x 5.

Example 3

At the beginning of the lesson, you read this problem:

If there are 5 books in each box and there are four boxes, how many total books are there?


Sometimes, it is helpful to draw a picture. The picture below represents the four boxes with 5 in each box:

 

5

 

5

5

5

 

Since there are four equal groups with five in each group, the addition sentence would be 5 + 5 + 5 + 5. The multiplication sentence would be 4 x 5 = 20. There are 20 total books.

Discuss with a parent or teacher:

  • What multiplication sentence would represent 10 + 10 + 10?
  • Does the order of the numbers in multiplication matter?

In the Got It? section, you will practice writing and solving multiplication and repeated addition problems as you play a game and complete interactive practice.

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