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Holt CA Course Adding, Subtracting, and Multiplying Decimals Warm Up Warm Up California Standards California Standards Lesson Presentation Lesson PresentationPreview

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Warm Up in Spiral Estimate by rounding to the nearest integer – – Multiply , , ,552 4, ,240 15

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Extension of NS2.3 Solve addition, subtraction, multiplication, and division problems, including those arising in concrete situations, that use positive and negative integers and combinations of these operations. (Also a review of 5 th grade NS2.1) California Standards

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Holt CA Course Adding, Subtracting, and Multiplying Decimals One of the coolest summers on record in the Midwest was in The average summertime temperature that year was 66.8°F. Normally, the average temperature is 4°F higher than it was in To find the normal average summertime temperature in the Midwest, you can add 66.8°F and 4°F.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Use zero as a placeholder so that both numbers have the same number of digits after their decimal points. Add each column just as you would add integers. Line up the decimal points The normal average summertime temperature in the Midwest is 70.8°F.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Add. Estimate to check whether the answer is reasonable Line up the decimal points. Use zero as a placeholder Add. Estimate = is a reasonable answer. Additional Example 1A: Adding and Subtracting Decimals

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Holt CA Course Adding, Subtracting, and Multiplying Decimals 28 – Use zeros as placeholders. – Subtract Line up the decimal points. Additional Example 1B: Adding and Subtracting Decimals Subtract. Estimate to check whether the answer is reasonable. Estimate 28 – 16 = is a reasonable answer.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Add. Estimate to check whether the answer is is reasonable Line up the decimal points. Use zero as a placeholder Add. Estimate = is a reasonable answer. Check It Out! Example 1A

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Check It Out! Example 1B Subtract. Estimate to check whether the answer is reasonable. Estimate 34 – 12 = is a reasonable answer. 34 – Use zeros as placeholders. – Subtract Line up the decimal points.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals To multiply decimals, multiply as you would with integers, and then place the decimal point. The product should have the same number of decimal places as the sum of the decimal places in the factors. 7 8 decimal place 2 decimal places + Same digits 0.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Multiply. Estimate to check whether the answer is reasonable. Additional Example 2A: Multiplying Decimals 2.4 2 1 decimal place 0 decimal places 2.4 = 1 decimal place Estimate 2 2 = is a reasonable answer.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Multiply. Estimate to check whether the answer is reasonable. Additional Example 2B: Multiplying Decimals –3.84 decimal places 1 decimal place –3.84 0.9 – = 3 decimal places Estimate –4 1 = –4 –3.456 is a reasonable answer.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Multiply. Estimate to check whether the answer is reasonable. Check It Out! Example 2A 3.2 decimal place 3.2 = 2 decimal places Estimate 3 2 = is a reasonable answer.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Multiply. Estimate to check whether the answer is reasonable. Check It Out! Example 2B –2.96 decimal places 1 decimal place –2.96 0.7 – = 3 decimal places Estimate –3 1 = –3 –2.072 is a reasonable answer.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals To find your weight on another planet, multiply the relative gravitational pull of the planet and your weight. The relative gravitational pull on Mars is What would a person who weighs 85 pounds on Earth weigh on Mars? Additional Example 3: Application 2 decimal places 0 decimal places 0.38 = 2 decimal places The person would weigh 32.3 pounds on Mars.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Check It Out! Example 3 Jet fuel weighs approximately 6.2 pounds per gallon. If a plane was serviced with 1,012 gallons of fuel, how many pounds of fuel were used? 1 decimal place = 1 decimal place 6.2 1,012 0 decimal places A plane would use 6,274.4 pounds of fuel.

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Holt CA Course Adding, Subtracting, and Multiplying Decimals Lesson Quiz 2.56; Estimate: 7 – 4 = ; Estimate: = 21 Add, subtract, or multiply. Estimate to check whether your answer is reasonable – (–5.4) 5. Dennis runs 7.2 miles per day. How far does he run in 5 days? 13.94; Estimate: 3 4 = 12 –41.148; Estimate: 8 (–5) = –40 36 miles

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