4-9 Multiplying Fractions by Whole Numbers Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day

Warm Up Multiply Course Multiplying Fractions by Whole Numbers      15

Problem of the Day The length of three dowels are 13 inches, 27 inches, and 19 inches. How can you use the three dowels to mark off a length of 5 inches? – 27 Course Multiplying Fractions by Whole Numbers

Learn to multiply fractions by whole numbers. Course Multiplying Fractions by Whole Numbers

Course Multiplying Fractions by Whole Numbers Recall that multiplication by a whole number can be represented as repeated addition. For example, 4 5 = You can multiply a whole number by a fraction using the same method. + + = 3 = 3 4 __ 1 4

Course Multiplying Fractions by Whole Numbers 3 1 __ ______ 3 4 __ There is another way to multiply with fractions. Remember that a whole number can be written as an improper fraction with 1 in the denominator. So 3 =. 3 1 __ == Multiply numerators Multiply denominators

Course Multiplying Fractions by Whole Numbers Additional Example 1A: Multiplying Fractions and Whole Numbers Multiply. Write the answer in simplest form. 1 9 __ ______ 7 9 __ = = Write 7 as a fraction. Multiply numerators and denominators. A. 7

Course Multiplying Fractions by Whole Numbers Additional Example 1B: Multiplying Fractions and Whole Numbers Multiply. Write the answer in simplest form. 1 8 __ ______ 6 8 __ = = Write 6 as a fraction. Multiply numerators and denominators. 3 4 __ = Write your answer in simplest form. B. 6

Course Multiplying Fractions by Whole Numbers Additional Example 1C: Multiplying Fractions and Whole Numbers Multiply. Write the answer in simplest form. 2 3 __ ______ 16 3 ___ = = Write 8 as a fraction. Multiply numerators and denominators. 1 3 __ or 5 C. 8

Course Multiplying Fractions by Whole Numbers Try This: Example 1A Multiply. Write the answer in simplest form. 1 5 __ ______ 4 5 __ = = Write 4 as a fraction. Multiply numerators and denominators. A. 4

Course Multiplying Fractions by Whole Numbers Try This: Example 1B Multiply. Write the answer in simplest form. 1 6 __ ______ 3 6 __ = = Write 3 as a fraction. Multiply numerators and denominators. 1 2 __ = Write your answer in simplest form. B. 3

Course Multiplying Fractions by Whole Numbers Try This: Example 1C Multiply. Write the answer in simplest form. 3 4 __ ______ 27 4 ___ = = Write 9 as a fraction. Multiply numerators and denominators. 3 4 __ or 6 C. 9

Course Multiplying Fractions by Whole Numbers Additional Example 2A: Evaluating Fraction Expression Evaluate 4x for the value of x. Write the answer in simplest form ___ 4 1 __ 1 10 ___ 4 10 ___ = Write the expression. 4x4x ___ = 2 5 __ Multiply. Substitute for x ___ Write your answer in simplest form. A. x =

Course Multiplying Fractions by Whole Numbers Additional Example 2B: Evaluating Fraction Expression Evaluate 4x for the value of x. Write the answer in simplest form. 3 8 __ ___ = Write the expression. 4x4x __ = 3 2 Multiply. Substitute for x. 3 8 __ Write your answer in simplest form. 1 2 __,or 1 B. x =

Course Multiplying Fractions by Whole Numbers Try This: Example 2A Evaluate 3x for the value of x. Write the answer in simplest form. 1 9 __ = Write the expression. 3x3x __ = 1 3 Multiply. Substitute for x. 1 9 __ Write your answer in simplest form. A. x =

Course Multiplying Fractions by Whole Numbers Try This: Example 2B Evaluate 3x for the value of x. Write the answer in simplest form. 4 7 __ ___ = Write the expression. 3x3x __ = Multiply. Substitute for x. 4 7 __ Write your answer in simplest form. 5 7 __ 1 B. x =

Course Multiplying Fractions by Whole Numbers Sometimes the denominator of an improper fraction will divide evenly into the numerator. When this happens, the improper fraction is equivalent to a whole number, not a mixed number. This makes sense if you remember that the fraction bar means “divided by” ___ = 4

Course Multiplying Fractions by Whole Numbers Additional Example 3: Application There are 25 students in the music club. Of those students, are also in the band. How many music club students are in the band? 3 5 __ 5 3 To find of 25, multiply ___ 3 5 __ 25 = 3 5 __ 75 5 ___ = = 15 There are 15 music club students in the band.

Course Multiplying Fractions by Whole Numbers Try This: Example 3 There are 18 saltwater fish in the aquarium. Of those fish, are blue. How many fish in the aquarium are blue? 2 3 __ 2 3 To find of 18, multiply ___ 2 3 __ 18 = 2 3 __ 36 3 ___ = = 12 There are 12 blue fish in the aquarium.

Course Multiplying Fractions by Whole Numbers Lesson Quiz Multiply. Write each answer in simplest form Evaluate 6x for each value of x. Write your answer in simplest form. 3. x = 4. x = 5. Alicia spent 15 minutes making a pizza. Of those minutes were spent rolling out the crust. How many minutes did Alicia spend rolling out the crust? 2 5 __ 1 10 __ minutes __, or __ 3 2