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

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

3. 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

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

5. 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.
= 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.

6. 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

7. 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.

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

9. 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.

10. 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!

11. 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: ÷ 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.

12. 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.

13. 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.

14. 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: ÷ 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.

15. 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 $ 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
$ $0.75 = $1.73
Kevin spent a total of $1.73.

16. 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.
$ $0.15 = $1.94
John spent a total of $1.94.

17. 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.
÷ 5
÷ (–6)
÷ 24
÷ 12
5. Allison swam 5 sprint laps in the pool. If her times were 17.5, 19.3, 20.6, 17.4, and seconds per lap, what was her average lap time?
3.1
–3.8
3.02
0.7
18.3 s