New SAT Math Workbook

Petersonscom operations with fractions 23 2

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Unformatted text preview: act (A) (B) (C) (D) (E) 3 9 from . 5 11 12 − 55 12 55 1 3 8 3 4 5 1 2 from the sum of and . 8 4 3 3. 5 3 The sum of and is 17 15 126 (A) 255 40 (B) 255 8 (C) 32 40 (D) 32 126 (E) 265 3 5 From the sum of and subtract the sum of 4 6 1 2 5. Subtract (A) (B) (C) (D) (E) 2 3 2 11 24 8 15 7 24 4 and 3 . (A) (B) (C) (D) (E) 2 1 2 36 70 2 3 5 24 www.petersons.com Operations with Fractions 23 2. MULTIPLICATION AND DIVISION In multiplying fractions, always try to divide out any common factor of any denominator with any numerator to keep your numbers as small as possible. Remember that if all numbers divide out in the numerator, you are left with a numerator of 1. The same goes for the denominator. If all numbers in both numerator and denominator divide out, you are left with Example: Multiply Solution: 3 15 11 ⋅⋅ 5 33 45 1 or 1. 1 1 3 1 3 15 11 ⋅ ⋅ = 5 33 45 15 3 1 15 In dividing fractions, we multiply by the multiplicative inverse. Example: Divide Solution: 591 ⋅= 18 5 2 2 5 5 by 18 9 www.petersons.com 24 Chapter 2 Exercise 2 Work out each problem. Circle the letter that appears before your answer. 1. Find the product of (A) (B) 3 3 4 1 , 6, , and . 2 9 12 4. 2. 3. 1 3 14 (C) 23 1 (D) 36 5 (E) 12 72 1 Find ⋅ ÷ . 83 8 3 (A) 14 7 (B) 96 21 (C) 128 14 (D) 3 8 (E) 3 3 1 3 ÷ ⋅ is equal to 5 2 10 5. 2 7 of . 3 12 7 (A) 8 7 (B) 9 8 (C) 7 8 (D) 9 7 (E) 18 5 Divide 5 by . 12 25 (A) 12 1 (B) 12 5 (C) 12 Find (D) (E) 12 12 5 (A) (B) (C) (D) (E) 4 1 4 12 5 5 12 12 15 www.petersons.com Operations with Fractions 25 3. SIMPLIFYING FRACTIONS All fractional answers should be left in simplest form. There should be no factor that can still be divided into numerator and denominator. In simplifying fractions involving very large numbers, it is helpful to tell at a glance whether or not a given number will divide evenly into both numerator and denominator. Certain tests for divisibility assist with this. If a number is divisible by 2 3 4 5 6 8 9 Example: By what single digit number should we simplify 428...
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