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Five-Minute Check (over Lesson 3–5)
Main Idea
Example 1:Multiply Decimals
Example 2:Multiply Decimals
Example 3:Annex Zeros in the Product
Example 4:Annex Zeros in the Product
Example 5:Multiply by 10, 100, or 1,000
5
Multiply Decimals
Find 18.9 × 4.
Method 1 Use estimation.
Round 18.9 to 19.18.9 × 4 → 19 × 4 or 76
18.9× 4
3
Since the estimate is 76, place the decimal point after the 5.
6
3
.7
Multiply Decimals
Method 2 Count decimal places.
Answer: 75.6
one decimal place
Count one decimal place from the right.
5
18.9× 4
3
6
3
.7
Multiply Decimals
Find 0.56 × 7.
Method 1 Use estimation.
Round 0.56 to 0.5.0.56 × 7 → 0.5 × 7 or 3.5
Since the estimate is 3.5, place the decimal point after the 3.
9
0.56× 7
2
4
.3
Multiply Decimals
Answer: 3.92
Method 2 Count decimal places.
two decimal places
Count two decimal places from the right.
9
0.56× 7
2
4
.3
Annex Zeros in the Product
Find 3 × 0.016.
Answer: 0.048
three decimal places
Annex a zero on the left of 48 to make three decimal places.
48
1
0
0.016× 3 0.
ALGEBRA Evaluate 5g if g = 0.0091.
5g = 5 × 0.0091 Replace g with 0.0091.
Answer: 0.0455
Annex Zeros in the Product
four decimal places
Annex a zero to make four decimal places.
0.0455
0.0091× 5
1. A
2. B
3. C
4. D
A B C D
0% 0%0%0%
A. 0.0186
B. 0.186
C. 1.86
D. 18.6
ALGEBRA Evaluate 3x if x = 0.0062.
MENTAL MATH Find 3.25 × 100.
Method 1 Use paper and pencil.
Multiply by 10, 100, or 1,000
Answer: 325.00
two decimal places
two decimal places
325.00
100× 3.25 500 2000 30000 +
Method 2 Use mental math.
Move the decimal point to the right the same number of zeros that are in 100, or 2 places.
Answer: 325
Multiply by 10, 100, or 1,000
3.25 × 100 = 3.25
Five-Minute Check (over Lesson 3–5)
Image Bank
Math Tools
Modeling Decimals
Dividing Decimals
Modeling Decimals
1. A
2. B
3. C
4. D
A B C D
0% 0%0%0%
Find 8.7 + 11.5.
A. 19.2
B. 20.1
C. 20.2
D. 21.2
(over Lesson 3-5)
1. A
2. B
3. C
4. D
A B C D
0% 0%0%0%
Find 17.15 + 12.96.
A. 29.11
B. 29.95
C. 30.06
D. 30.11
(over Lesson 3-5)
1. A
2. B
3. C
4. D
A B C D
0% 0%0%0%
Find 34.64 – 27.18.
A. 7.22
B. 7.46
C. 7.72
D. 8.56
(over Lesson 3-5)
1. A
2. B
3. C
4. D
A B C D
0% 0%0%0%
Evaluate the expression a – b if a = 105.8 and b = 95.9.
A. 8.9
B. 9.7
C. 9.9
D. 10.3
(over Lesson 3-5)
1. A
2. B
3. C
4. D
0% 0%0%0%
Based on the information in the table, how much greater was Michael Young’s batting average than Jose Reyes’ batting average?
(over Lesson 3-5)
A. .058
B. .055
C. .041
D. .028