3-6 Multiplying Decimals Warm Up Problem of the Day Course 1 Warm Up Problem of the Day Lesson Presentation

3-6 Multiplying Decimals Warm Up Multiply. 1. 87  320 27,840 Course 1 3-6 Multiplying Decimals Warm Up Multiply. 1. 87  320 27,840 2. 943  800 754,400 3. 3,806  10 38,060 4. 1,207  100 120,700 5. 72  196 14,112 6. 120  523 62,760

3-6 Multiplying Decimals Problem of the Day Course 1 3-6 Multiplying Decimals Problem of the Day Carmen and Rita sold homemade oatmeal cookies. After 8 days, they had sales totaling $70. Each day, their sales were $0.50 higher than the previous day. What were their sales on the first day? $7.00

3-6 Multiplying Decimals Course 1 3-6 Multiplying Decimals Learn to multiply decimals by whole numbers and by decimals.

Additional Example 1: Science Application Course 1 3-6 Multiplying Decimals Additional Example 1: Science Application Something that weighs 1 lb on Earth weighs 0.17 lb on the Moon. How much would a 4 lb dumbbell weigh on the Moon? 4  0.17 You can think of multiplication by a whole number as a repeated addition. 0.17 0.17 0.17 + _____ 0.17 0.68

Additional Example 1 Continued Course 1 3-6 Multiplying Decimals Additional Example 1 Continued Something that weighs 1 lb on Earth weighs 0.17 lb on the Moon. How much would a 4 lb dumbbell weigh on the Moon? You can also multiply as you would with whole numbers. Place the decimal point by adding the number of decimal places in the numbers multiplied. 0.17 2 decimal places 4 + 0 decimal places  _____ 2 decimal places 0.68 A 4 lb dumbbell on Earth weighs 0.68 lb on the Moon.

3-6 Multiplying Decimals Try This: Example 1 Course 1 3-6 Multiplying Decimals Try This: Example 1 Something that weighs 1 lb on Earth weighs 0.17 lb on the Moon. How much would a 7 lb dumbbell weigh on the Moon? 7  0.17 You can think of multiplication by a whole number as a repeated addition. 0.17 0.17 0.17 0.17 0.17 0.17 0.17 + _____ 1.19

Try This: Example 1 Continued Course 1 3-6 Multiplying Decimals Try This: Example 1 Continued Something that weighs 1 lb on Earth weighs 0.17 lb on the Moon. How much would a 7 lb dumbbell weigh on the Moon? You can also multiply as you would with whole numbers. Place the decimal point by adding the number of decimal places in the numbers multiplied. 0.17 2 decimal places  _____ 7 + 0 decimal places 2 decimal places 1.19 A 7 lb dumbbell on Earth weighs 1.19 lb on the Moon.

Additional Example 2A: Multiplying a Decimal by a Decimal Course 1 3-6 Multiplying Decimals Additional Example 2A: Multiplying a Decimal by a Decimal Find the product. A. 0.3  0.4 Multiply. Then place the decimal point. 1 decimal place 0.3  + 1 decimal place 0.4 2 decimal places 0.12

Additional Example 2B: Multiplying a Decimal by a Decimal Course 1 3-6 Multiplying Decimals Additional Example 2B: Multiplying a Decimal by a Decimal B. 0.07  0.8 Estimate the product. 0.8 is close to 1. 0.07  1 = 0.07 Multiply. Then place the decimal point. 2 decimal places 0.07 + 1 decimal place  0.8 3 decimal places; use a placeholder zero 0.056 0.056 is close to the estimate of 0.07. The answer is reasonable.

Additional Example 2C: Multiplying a Decimal by a Decimal Course 1 3-6 Multiplying Decimals Additional Example 2C: Multiplying a Decimal by a Decimal C. 1.34  2.5 Estimate the product. Round each factor to the nearest whole number. 1  3 = 3 Multiply. Then place the decimal point. 1.34  2.5 2 decimal places 670 + 1 decimal place 2680 3 decimal places 3.350 3.350 is close to the estimate of 3. The answer is reasonable.

3-6 Multiplying Decimals  Try This: Example 2A Find each product. Course 1 3-6 Multiplying Decimals Try This: Example 2A Find each product. A. 0.5  0.2 Multiply. Then place the decimal point. 1 decimal place 0.5  + 1 decimal place 0.2 2 decimal places 0.10

3-6 Multiplying Decimals  Try This: Example 2B B. 0.03  0.9 Course 1 3-6 Multiplying Decimals Try This: Example 2B B. 0.03  0.9 Estimate the product. 0.9 is close to 1. 0.03  1 = 0.03 Multiply. Then place the decimal point. 2 decimal places 0.03 + 1 decimal place  0.9 3 decimal places; use a placeholder zero 0.027 0.027 is close to the estimate of 0.03. The answer is reasonable.

3-6 Multiplying Decimals  Try This: Example 2C C. 3.80  3.3 Course 1 3-6 Multiplying Decimals Try This: Example 2C C. 3.80  3.3 Estimate the product. Round each factor to the nearest whole number. 4  3 = 12 Multiply. Then place the decimal point. 3.80  3.3 2 decimal places 1140 + 1 decimal places 11400 3 decimal places 12.540 12.54 is close to the estimate of 12. The answer is reasonable.

Additional Example 3A: Evaluating Decimal Expressions Course 1 3-6 Multiplying Decimals Additional Example 3A: Evaluating Decimal Expressions Evaluate 5x for each value of x. A. x = 3.062 Substitute 3.062 for x. 5x = 5(3.062) 3 decimal places 3.062  5 + 0 decimal places 15.310 3 decimal places These notations all mean multiply 3 times x. 3 • x 3x 3(x) Remember!

Additional Example 3B: Evaluating Decimal Expressions Course 1 3-6 Multiplying Decimals Additional Example 3B: Evaluating Decimal Expressions B. x = 4.79 Substitute 4.79 for x. 5x = 5(4.79) 2 decimal places 4.79 + 0 decimal places  5 23.95 2 decimal places

3-6 Multiplying Decimals  Try This: Example 3A Course 1 3-6 Multiplying Decimals Try This: Example 3A Evaluate 5x for each value of x. A. x = 2.012 Substitute 2.012 for x. 5x = 5(2.012) 3 decimal places 2.012 + 0 decimal places  5 10.060 3 decimal places

3-6 Multiplying Decimals  Try This: Example 3B B. x = 6.22 Course 1 3-6 Multiplying Decimals Try This: Example 3B B. x = 6.22 Substitute 6.22 for x. 5x = 5(6.22) 2 decimal places 6.22  5 + 0 decimal places 31.10 2 decimal places

Insert Lesson Title Here Course 1 3-6 Multiplying Decimals Insert Lesson Title Here Lesson Quiz Find each product. 1. 0.8 2. 0.006  0.07 Evaluate 8x for each value of x.  0.07 0.056 0.00042 3. x = 2.705 4. x = 0.804 21.64 6.432 5. “Pick your own” peaches sell for $0.95 per pound. You picked 92 pounds of peaches. How much were you charged? $87.40