Finding a Percent of a Number COURSE 2 LESSON 6-4 Finding a Percent of a Number Find each answer using mental math. a. 49% of 300 What you think 49% is 50% – 1% 50% of 300 is 0.5 • 300, or 150. 1% of 300 is 0.01 • 300, or 3. So 150 – 3 = 147. Why it works 0.49 • 300 Write 49% as a decimal. (0.50 – 0.01) • 300 Substitute 0.50 – 0.01 for 0.49. (0.50 • 300) – (0.01 • 300) Use the Distributive Property. 150 – 3 Multiply. 147 Simplify. 6-4

Finding a Percent of a Number COURSE 2 LESSON 6-4 Finding a Percent of a Number (continued) b. 11% of 7220 What you think 11% is 10% + 1% 10% of 720 is 0.1 • 720, or 72. 1% of 720 is 0.01 • 720, or 7.2. So 72 + 7.2 = 79.2. Why it works 0.11 • 720 Write 11% as a decimal. (0.10 + 0.01) • 720 Substitute 0.10 + 0.01 for 0.11. (0.10 • 720) + (0.01 • 720) Use the Distributive Property. 72 + 7.2 Multiply. 79.2 Simplify. 6-4

Finding a Percent of a Number COURSE 2 LESSON 6-4 Finding a Percent of a Number Estimate each answer. a. 76% of 405 Write an expression. 76% • 405 3 4 • 400 = 300 Use compatible numbers such as and 400. Check for Reasonableness  76% of 405 is 0.76 • 405, or 307.8, which is close to the estimate 300. The answer is reasonable. b. 12% of 5,575 12% • 5,575 Write an expression. • 6,000 = 600 1 10 Use compatible numbers such as and 6,000. Check for Reasonableness  12% of 5,575 is 0.12 • 5,575, or 669, which is close to the estimate 600. The answer is reasonable. 6-4

Finding a Percent of a Number COURSE 2 LESSON 6-4 Finding a Percent of a Number (continued) c. 48% of 925 Write an expression. 48% • 925 1 2 • 900 = 450 Use compatible numbers such as and 900. Check for Reasonableness  48% of 925 is 0.48 • 925, or 444, which is close to the estimate 450. The answer is reasonable. 6-4

Finding a Percent of a Number COURSE 2 LESSON 6-4 Finding a Percent of a Number Find the percent of each number. 1. 40% of 90 2. 120% of 45 3. 3.5% of 700 4. 90% of 650 36 54 24.5 585 6-4