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Do Now Estimate by rounding to the nearest integer. 1. 3.62 + 4.1 2. 7.47 + (–8.23) 3. 8.52 – 3.16 4. 5.826 + 11.729 8 –1 6 Course 2 3-2 Adding and Subtracting.

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Presentation on theme: "Do Now Estimate by rounding to the nearest integer. 1. 3.62 + 4.1 2. 7.47 + (–8.23) 3. 8.52 – 3.16 4. 5.826 + 11.729 8 –1 6 Course 2 3-2 Adding and Subtracting."— Presentation transcript:

1 Do Now Estimate by rounding to the nearest integer (–8.23) – –1 6 Course Adding and Subtracting Decimals 18 Hwk: p 25, 26

2 Problem of the Day Complete the magic square. The sum of each row, column, and diagonal must be the same number Course Adding and Subtracting Decimals

3 EQ: How do I add/subtract/multiply/divide decimals ? Course Adding and Subtracting Decimals M7N1.c Add, subtract, multiply, and divide positive and negative rational numbers

4 Course Adding and Subtracting 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 Add 66.8 and 4

5 Course Adding and Subtracting Decimals Estimate = 16

6 Course Adding and Subtracting Decimals Estimate = 22

7 Insert Lesson Title Here When adding numbers with the same sign, find the sum of their absolute values. Then use the sign of the numbers. Remember! Course Adding and Subtracting Decimals

8 Course Adding and Subtracting Decimals – ( – ) Estimate – 8 + ( – 11) = – 19

9 Course Adding and Subtracting Decimals Estimate = 20

10 Course Adding and Subtracting Decimals Estimate = 38

11 Course Adding and Subtracting Decimals – ( – ) = – Estimate – 8 + ( – 14) = – 22

12 Course Adding and Subtracting Decimals A – B. 28 – –

13 Course Adding and Subtracting Decimals A – B. 34 – –

14 Course Adding and Subtracting Decimals During one month in the United States, million commuter trips were taken on buses, and million commuter trips were taken on light rail. What was the total number of trips taken on buses and light rail? The total number of trips was million.

15 Insert Lesson Title Here Course Adding and Subtracting Decimals The total number of bushels was million. In 1999, million bushels of corn were grown in the United States. In 2000, the harvest yielded million bushels. What was the total production for those two years?

16 Course Multiplying Decimals To multiply decimals, multiply as you would with integers. To place the decimal point in the product, count the number of decimal places in each factor. The product should have the same number of decimal places in the factors decimal place 2 decimal places + Same digits 0.

17 Multiply. Additional Example 1: Multiplying Integers by Decimals Course Multiplying Decimals A. 7 · B. –3 · 0.03 – – 0.09

18 Multiply. Additional Example 1: Multiplying Integers by Decimals Course Multiplying Decimals C ·

19 Multiply. Check It Out: Example 1 Course Multiplying Decimals A. 8 · B. –2 · 0.04 – –0.08

20 Multiply. Check It Out: Example 1 Course Multiplying Decimals C ·

21 Multiply. Additional Example 2A: Multiplying Decimals by Decimals Course Multiplying Decimals 2.4 · Estimate 2 · 2 = 4

22 Multiply. Additional Example 2B: Multiplying Decimals by Decimals Course Multiplying Decimals –3.84 · 0.9 – –3.456 Estimate –4 · 1 = –4

23 Multiply. Check It Out: Example 2A Course Multiplying Decimals 3.2 · Estimate 3 · 2 = 6

24 Multiply. Check It Out: Example 2B Course Multiplying Decimals –2.96 · 0.7 – –2.072 Estimate –3 · 1 = –3

25 Quiz Insert Lesson Title Here 2.56; Course Adding and Subtracting Decimals 21.25;–27.66; – ; – ( – 19.2) – 4.16 Subtract.

26 Quiz Insert Lesson Title Here Course Adding and Subtracting Decimals Subtract. 5. Renee finished her first lap in the 200 m freestyle event in seconds. She completed the second lap in seconds. By how much did her time increase in the second lap? Estimate to check whether your answer is reasonable seconds;

27 Lesson Quiz Multiply · · · · (–5.4) 10. Dennis runs 7.2 miles per day. How far does he run in 5 days? Insert Lesson Title Here 13.94; –41.148; Course Multiplying Decimals 36 miles


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