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Published byAngela Cox Modified over 9 years ago
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5-2 6 th grade math Adding and Subtracting with Like Denominators
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Objectives Add and subtract fractions and mixed numbers with like denominators. Why? To know how to solve all types of number sense problems.
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California State Standards NS 2.1: Solve problems involving addition, subtraction, … of positive fractions and explain why a particular operation was used for a given situation… NS 2.0 : Calculate and solve problems involving addition, subtraction, … MR 2.1: Use estimation to verify the reasonableness of calculated results.
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Vocabulary Like denominators- – fractions whose denominators are the same + Simplify (simplest form, reduced form)- – when the GCF of the numerator and denominator is one 2 = (divide by 5) = 1 10 = (divide by 5) 5
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How to Add Fractions with like Denominators Example 1. I+ 1.Add the numerator. 2.Keep the denominators the same. 3.Simplify, if possible. Here’s how to solve: I+ = 4 = 8 1 2
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How to Add Fractions with like Denominators, with a “Mixed/Improper” Answers. Example 2. 9 3 + 7 7 8 8 1.Add the fractions. 2.Add the whole numbers. 3.Simplify the sum. 9 3 8 7 + 8 = 10 8 =16 10 8 10/8 = 1 2/10 = 1 + 16 = = 16
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How to Subtract Fractions with like Denominators Example 3 7 - 3 10 1.Subtract the numerators 2.Use the common denominator. 3.Simplify, if possible. 7 - 3 10 4 = 2 10 5
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How to Subtract Fractions with like Denominators, when needing “to borrow.” 4 -2-2 1.Rename the top fraction before you subtract, because < . 2.Subtract the fractions and then whole numbers. 3.Simplify, if possible. 4 -2-2 3 4 4 - 2 3 - 4 2 = 1 4 2 = 1 = 1
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Try It! 1) 11 - 4 15 15 2) + 3) - 4) 7 - 3 12 12 5) 8 - 2 9 9 Answers: 1) 7 15 2) 3) 4) 5)
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How it works …. 2) 1/8 + 3/8 = 4/8 = ½ 3) 7/8- 5/8 = 2/8 = ¼ 4)7/12 – 3/12 = 4/12 = 1/3 5)8/9 – 2/9 = 6/9 = 2/3
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Try some more!! 6) 4 - 2 7) 8 6 + 4 7 8 8 8) 3 6 + 1 5 7 7 9) 6 – 4 Answers: 6) 1 7) 13 5 8 8) 5 4 7 9) 1
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How it works! 6)4 1/3 – 2 2/3 = 3 3/ 3 – 2 2/3 1 1/3 7)8 6/8 + 4 7/8 = 13/8 = 1 5/8 8 + 4 = 12 12 + 1 5/8 = 13 5/8 8)3 6/7 + 1 5/7 11/7 = 1 4/7 3 + 1 = 4 4 + 1 4/7 = 5 4/7 9)S6 - 4 ¾ 5 4/4 - 4 ¾ = 1 ¼
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Objective Review Add and subtract fractions and mixed numbers with like denominators. Why? You know how to solve all types of number sense problems.
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Independent Practice 1.Complete problems 13-19. 2.Problems 20, 21 for a challenge. 3.Remember to copy the problem first. 4.Show all of your work! When finished: – If time, complete the Mixed Review problems 22-24. – If still more time, complete your Accelerated Math.
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