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Multiplying With Fractions

Multiplying With Fractions. Objectives. Students will be able to: Multiply fractions by fractions, whole numbers and mixed numbers Solve real world problems involving multiplying fractions Use the strategy of simplifying factors to make multiplying fraction problems easier.

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Multiplying With Fractions

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  1. Multiplying With Fractions

  2. Objectives • Students will be able to: • Multiply fractions by fractions, whole numbers and mixed numbers • Solve real world problems involving multiplying fractions • Use the strategy of simplifying factors to make multiplying fraction problems easier.

  3. Multiply Fractions:Just Follow These Easy Steps! • Multiply the numerators and write down the answer as your new numerator. • Multiply the denominators and write down the answer as your new denominator. • Simplify. THAT’S IT!!!

  4. Example 1 5 3 15 x = 32 8 4 There are no common factors for 15 and 32, so this fraction cannot be simplified.

  5. Example 2 3 2 6 1 x = = 9 36 6 4 This fraction can be reduced. Divide the numerator and denominator by the GCF, which is 6.

  6. Multiplying by a Whole Number If you want to multiply a fraction by a whole number, turn your whole number into a fraction by placing a 1 as the denominator. If your answer is improper, divide the bottom into the top. 4 20 80 16 x = = 5 5 1

  7. Another Example 15 1 5 15 x = = 1 6 6 2 15 and 6 have a GCF of 3. Five halves is improper, so we divide the bottom into the top. 2 2 5 4 2 1 2 1

  8. Simplifying Factors • Before you multiply, you can make the problem simpler. • You can find the GCF of any numerator and denominator. • Find a factor that equally divides the top number and bottom number, divide, and rewrite the problem.

  9. Example 1 In the second fraction, 8 and 16 have a GCF of 8. 5 8 1 x 16 2 7 8 ÷ 8 = 1 and 16 ÷ 8 = 2 Now, multiply with the simpler numbers. 5 x 1 = 5 and 7 x 2 = 14. 5 14

  10. Example 2 The top of the first fraction and the bottom of the second fraction have a common factor. The GCF of 2 and 12 is 2. 1 2 5 x 6 12 3 2 ÷ 2 = 1, and 12 ÷ 2 = 6. Now, multiply: 5 18

  11. To Multiply Mixed Numbers: • Change any mixed numbers to improper fractions. • Simplify factors. • Multiply numerators by numerators and denominators by denominators. • Simplify and/or change improper fractions back into mixed numbers.

  12. 1 Example 1 2 6 x 4 7 6 3 9 27 x = 2 4 7 14 1 14 27 13 1 14 14 13

  13. Example 2 1 3 4 3 x 6 5 3 15 5 25 18 x = 1 6 5 1 1 15

  14. Example 3 3 1 1 x 2 8 7 7 1 x = 8 16 2

  15. Word Problem • Sean spent ¾ of his homework time on math. Of that time, he spent 2/3 working with fractions. What fraction of Sean’s homework time did he spend working with fractions? What operation should we use? Multiplication ½ of Sean’s time was spent working with fractions. x = =

  16. Word Problem • Of the DVDs in the Crawford’s collection, 3/5 are Troy’s father’s. Of Troy’s father’s DVDs, 1/3 are comedies. What fraction of the Crawford’s DVDs are comedies owned by Troy’s father? What operation should we use? Multiplication 1/3 of the Crawford’s DVDs are comedies owned by Troy’s father. x = =

  17. Video Time! • Multiplying Fractions

  18. Video Time! • Multiplying Mixed Numbers

  19. Classwork: Check out this interactive game Soccer Shootout that helps you multiply fractions:

  20. Classwork: Use these Virtual Manipulativesto Model Multiplying Mixed Numbers.Homework Time:Multiplying Fractions HO

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