Dividing Decimals by Integers 3-4 Dividing Decimals by Integers Course 2 Warm Up Problem of the Day Lesson Presentation

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Warm Up Multiply or divide. 1. 3.4  2.6 8.84 2. 6.25  5 31.25 3. 8.14  1.1 8.954 4. 825 ÷ 15 55 5. 756 ÷ 12 63

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Problem of the Day Divide 60 by and add 10. What is your answer? 1 2 130

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Learn to divide decimals by integers.

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Elena received scores of 6.85, 6.95, 7.2, 7.1, and 6.9 on the balance beam at a gymnastics meet. To find her average score, add her scores and then divide by 5. 6.85 + 6.95 + 7.2 + 7.1 + 6.9 = 35 35 ÷ 5 = 7 Elena’s average score was 7, or 7.0. Notice that the sum of Elena’s scores is an integer. But what if the sum is not an integer? You can find the average score by dividing a decimal by a whole number.

Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Division can undo multiplication. 0.2 · 4 = 0.8 and 0.8 ÷ 4 = 0.2 Remember! 0.8 ÷ 4 0.8 divided into 4 equal groups The size of each group is the answer. Each group is 2 columns, or 0.2. 0.8 ÷ 4 = 0.2

Additional Example 1A: Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Additional Example 1A: Dividing Decimals by Integers Divide. Estimate to check whether each answer is reasonable. 36.75 ÷ 7 5 . 2 5 ) 36.75 7 Place the decimal point for the answer directly above the decimal under the division symbol. –35 1 7 –14 Divide as with whole numbers. 3 5 –35 Estimate 35 ÷ 7 = 5 5.25 is a reasonable answer.

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers 0.6 ÷ 0.3 = 2 Dividend Quotient Divisor 0.3 0.6 Remember! ) 2

Additional Example 1B: Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Additional Example 1B: Dividing Decimals by Integers Divide. Estimate to check whether each answer is reasonable. 0.87 ÷ 3 . 2 9 Place the decimal point for the answer directly above the decimal under the division symbol. Add a zero as a placeholder in the answer. ) 0.87 3 –6 27 –27 Divide as with whole numbers. Estimate 0.9 ÷ 3 = 0.3 0.29 is a reasonable answer.

Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers When you divide two numbers with different signs, the answer is negative. Remember!

Additional Example 1C: Dividing Decimals by Integers Course 2 3-4 Dividing Decimals by Integers Additional Example 1C: Dividing Decimals by Integers Divide. Estimate to check whether each answer is reasonable. 82.08 ÷ (–27) 3 . 4 27 ) 82.08 The signs are different. –81 Think: 82.08 ÷ 27. 1 –0 Place the decimal point for the answer directly above the decimal under the division symbol. 1 08 –108 82.08 ÷ (–27) = –3.04 Estimate 90 ÷ –30 = –3 The answer is reasonable.

Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Check It Out: Example 1A Divide. Estimate to check whether each answer is reasonable. 39.16 ÷ 4 9 . 7 9 ) 39.16 4 Place the decimal point for the answer directly above the decimal under the division symbol. –36 3 1 –28 Divide as with whole numbers. 3 6 –36 Estimate 40 ÷ 4 = 10 9.79 is a reasonable answer.

Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Check It Out: Example 1B Divide. Estimate to check whether each answer is reasonable. 0.56 ÷ 4 . 1 4 Place the decimal point for the answer directly above the decimal under the division symbol. Add a zero as a placeholder in the answer. ) 0.56 4 –4 16 –16 Divide as with whole numbers. Estimate 0.6 ÷ 4 = 0.15 0.14 is a reasonable answer.

Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Check It Out: Example 1C Divide. Estimate to check whether each answer is reasonable. 65.16 ÷ (–12) 5 . 4 3 12 ) 65.16 The signs are different. –60 Think: 65.16 ÷ 12 5 1 –48 Place the decimal point for the answer directly above the decimal under the division symbol. 36 –36 65.16 ÷ (–12) = –5.43 Estimate 60 ÷ –12 = –5 The answer is reasonable.

Additional Example 2: Money Application Course 2 3-4 Dividing Decimals by Integers Additional Example 2: Money Application You can buy juice by the bottle or case. Either way, it costs the same for each bottle. A case of 24 bottles of juice cost $23.52. Kevin bought a bag of peanuts for 75¢ and one bottle of juice. How much did Kevin spend in all? First find the cost for one bottle of juice by dividing the cost of a case by the number of bottles in a case. Then add the cost of a bag of peanuts. . 9 8 24 ) 23.52 Place the decimal point for the answer directly above the decimal under the division symbol. 21 6 1 92 –1 92 One bottle of juice costs $0.98 and a bag of peanuts costs $0.75 $0.98 + $0.75 = $1.73 Kevin spent a total of $1.73.

Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Check It Out: Example 2 Cookies at a store sell for $1.80 a dozen. The cost for each cookie is the same whether you buy them individually or by the dozen. John decided to buy 1 cookie and a quart of milk. The milk costs $1.79. How much did John have to pay? First find the cost of one cookie by dividing the cost of a dozen by 12. Then add the price for the milk. . 1 5 12 ) 1.80 Place the decimal point for the answer directly above the decimal under the division symbol. 1 2 60 – 60 One quart of milk costs $1.79 and one cookie costs $0.15. $1.79 + $0.15 = $1.94 John spent a total of $1.94.

Dividing Decimals by Integers Insert Lesson Title Here Course 2 3-4 Dividing Decimals by Integers Insert Lesson Title Here Lesson Quiz Divide. Estimate to check whether each answer is reasonable. 1. 15.5 ÷ 5 2. 22.8 ÷ (–6) 3. 72.48 ÷ 24 4. 8.4 ÷ 12 5. Allison swam 5 sprint laps in the pool. If her times were 17.5, 19.3, 20.6, 17.4, and 16.7 seconds per lap, what was her average lap time? 3.1 –3.8 3.02 0.7 18.3 s