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Multiply Fractions by a Number (Grade 4)




 


Videos and lessons to help Grade 4 students learn to apply and extend previous understandings of multiplication to multiply a fraction by a whole number.

A. Understand a fraction a/b as a multiple of 1/b.For example, use a visual fraction model to represent 5/4 as the product 5 — (1/4), recording the conclusion by the equation 5/4 = 5 — (1/4).

B. Understand a multiple of a/b as a multiple of 1/b, and use this understanding to multiply a fraction by a whole number. For example, use a visual fraction model to express 3 — (2/5) as 6 — (1/5), recognizing this product as 6/5. (In general, n — (a/b) = (n — a)/b.)

C. Solve word problems involving multiplication of a fraction by a whole number, e.g., by using visual fraction models and equations to represent the problem. For example, if each person at a party will eat 3/8 of a pound of roast beef, and there will be 5 people at the party, how many pounds of roast beef will be needed? Between what two whole numbers does your answer lie?

Common Core: 4.NF.4

Suggested Learning Targets

  • I can explain why a/b = a × 1/b using models. For example, 3/4 = 1/4 + 1/4 + 1/4 = (3 × 1/4).
  • I can decompose a fraction into multiple unit fractions. 5 × 7/8 = 5 × (7 × 1/8) = (5 × 7) × 1/8 = 35 × 1/8 or 35/8.
  • I can solve word problems that involve a whole number and a fraction.


Related Topics:
More Lessons for Grade 4

Common Core for Grade 4

Using Visual Models and Repeated Addition

Understand a/b as a multiple of 1/b and solve word problems involving multiplication (4.NF.4a)
In this lesson you will learn how to multiply a fraction by a whole number by using visual models and repeated addition.





Multiply fractions by whole numbers using models - 4.NF.4
In this lesson you will learn how to multiply fractions by a whole number using visual fraction models.


Multiply fractions by whole numbers using repeated addition
In this lesson you will learn how to multiply fractions by a whole number using repeated addition.



 

Using Mathematical Model

Multiplying fractions and whole numbers.


Multiply a fraction by a whole number.




Multiplying Fractions and Whole Numbers.


Word Problems

4.NF.4.c - Fraction of a Set Word Problems (Singapore Math)
This video applies multiplying a fraction by a whole number to solve word problems. He uses the Singapore math modeling strategy of a bar model and the "unitary method" to illustrate 4.NF.4.c in the grade 4 Common Core Standards for Mathematics.
Example: Sean has 63 classical songs on his mp3 player. That's 7/8 of his entire collection. How many songs does Sean have altogether?



 

Multiplying Fractions and Whole Numbers -Word Problems
This video walkthrough lesson takes an in-depth look at multiplying fractions and whole numbers in a word problem format.
Example: Kayen drinks 3/4 of a bottle of coconut delight everyday. How much juice will he drink in five days?


Multiplying Fractions By Whole Numbers - Pizza by the Fraction
Example: Maria and Luigi decide to open up a pizza shape. For each pizza they charge $12. It's an additional $3 per topping for each whole pizza. Pizza are scaled according to the size of each slice. How much would they charge for each slice in the pizza shown below?




Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.


You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.


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