Fractions and Whole Numbers: Multiplying and Dividing Techniques
Learn how to estimate fractions using compatible numbers, multiply fractions with whole numbers, and perform various fraction multiplication and division operations. Includes examples for each concept.
Fractions and Whole Numbers: Multiplying and Dividing Techniques
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Presentation Transcript
2-1B: Estimating Fractions When do I Use…. Compatible numbers – when you are estimating a fraction & a whole number. Ex: ¼ x 25 = ¼ x 24 = 6 0, ½, 1 – when you are estimating with 2 proper fractions. Ex: 5311 6 8 2 2 Whole numbers – when you are estimating mixed numbers. Ex: 5 ¼ x 6 ¾ = 5 x 7 = 35 x = 1 x =
2-1D Multiply fractions & Whole Numbers • Write the Whole Number as a fraction by placing it over 1. • If you can, cross cancel & then multiply the numerators and the denominators (key concept – p. 96) 8 x ¼ = 8 12 1 4 1 2 x = or 2 1
2 – 2 (B) Multiply Fractons Multiply 2 Proper Fractions 2 1102 5 11 11 10410101 12 1 12 3 3 = x 1 1 Multiply a Proper Fraction & Whole number with a Mixed Number answer. 4 = x = 3 x = 3 Change the Improper fraction to a Mixed number
2-2 (C & D) Multiplying fractions and Mixed Numbers • Change the mixed numbers into Improper fractions • Check to see if you can cross cancel. • Multiply and Simplify. • If your answer is an Improper fraction you will need to change it into a Mixed Number. Ex: 2585202 3 6 36 9 9 4 2 x 2 x = = 3
2-3 (B – D) Dividing Fractions & Mixed Numbers To DIVIDE fractions – flip the 2nd fraction and then multiply. To DIVIDE Mixed Numbers you need to: • change the Mixed Number to an Improper fraction. • flip the 2nd fraction. • multiply. Ex: 51517161361 6 16 615 45 45 8 = = 2 ÷ = x 3 3