Answer:
1. ANS: C
To round to the nearest integer, look at the digit in the tenths place. If it is greater than or equal to 5, round to
the next integer. If it is less than 5, keep the same integer.
53.8 + 13.8 ≈ 54 + 14 = 68
Feedback
A Perform the correct operation.
B To round to the nearest integer, look at the digit in the tenths place. If it is greater than
or equal to 5, round to the next integer. If it is less than 5, keep the same integer.
C Correct!
D Perform the correct operation.
PTS: 1 DIF: Basic REF: Page 150
OBJ: 3-1.1 Estimating Sums and Differences of Decimals NAT: 8.1.2.b
TOP: 3-1 Estimate with Decimals KEY: decimal | difference | estimate | sum
2. ANS: A
Round each number to the nearest nonzero integer or to a number that is easy to multiply.
–25.46 • 18.73 ≈ –25 • 20 = –500
Feedback
A Correct!
B Multiply, not add.
C Round each number to the nearest nonzero integer or to a number that is easy to
multiply, and then multiply.
D Check the signs.
PTS: 1 DIF: Average REF: Page 151
OBJ: 3-1.2 Estimating Products and Quotients of Decimals NAT: 8.1.2.b
TOP: 3-1 Estimate with Decimals KEY: decimal | estimate | product | quotient
3. ANS: D
Round the numbers so that they divide without leaving a remainder.
40.7 ÷ (–4.4) ≈ 40 ÷ (–5) = –8
Feedback
A Round the numbers so that they divide without leaving a remainder, and then divide.
B Check the signs.
C Perform the correct operation.
D Correct!
PTS: 1 DIF: Average REF: Page 151
OBJ: 3-1.2 Estimating Products and Quotients of Decimals NAT: 8.1.2.b
TOP: 3-1 Estimate with Decimals KEY: decimal | estimate | product | quotient
ID: A
2
4. ANS: A
An estimate can help you decide whether Maria’s calculation is reasonable.
To estimate, round each number to the nearest whole number. Then, add.
The estimate 93 + 89 + 97 + 93 + 86 = 458 is equivalent to Maria’s calculation, so 458 is a reasonable
answer.
Feedback
A Correct!
B To estimate, round each number to the nearest whole number.
PTS: 1 DIF: Average REF: Page 151 OBJ: 3-1.3 Application
NAT: 8.1.3.g TOP: 3-1 Estimate with Decimals KEY: decimal | estimate | quotient | sum
5. ANS: D
Line up the decimal points, and then add.
31.9
+ 6.9
38.8
Feedback
A Check your calculations.
B Line up the decimal points, and then add.
C Place the decimal point in the correct location.
D Correct!
PTS: 1 DIF: Basic REF: Page 154 OBJ: 3-2.1 Adding Decimals
NAT: 8.1.3.a TOP: 3-2 Adding and Subtracting Decimals
KEY: addition | decimal
6. ANS: D
Line up the decimal points, and then subtract. If necessary, use zeros as placeholders and/or regroup.
91.4
− 87.7
3.7
Feedback
A Check your calculations.
B Line up the decimal points, and then subtract.
C Perform the correct operation.
D Correct!
PTS: 1 DIF: Average REF: Page 155 OBJ: 3-2.2 Subtracting Decimals
NAT: 8.1.3.a TOP: 3-2 Adding and Subtracting Decimals
KEY: decimal | subtraction
ID: A
3
7. ANS: D
Line up the decimal points, and then subtract. If necessary, regroup.
433.4
− 347.9
85.5
Mr. Romito drove 85.5 miles more miles on the first day than on the second day.
Feedback
A Line up the decimal points, and then subtract.
B Place the decimal point in the correct location.
C Check your calculations.
D Correct!
PTS: 1 DIF: Average REF: Page 155 OBJ: 3-2.3 Application
NAT: 8.1.3.g TOP: 3-2 Adding and Subtracting Decimals
KEY: addition | decimal | subtraction
8. ANS: B
Line up the decimal points, and then add.
14.91
+ 3.34
18.25
The corned beef and the cabbage cost $18.25.
Feedback
A Check your calculations.
B Correct!
C Line up the decimal points, and then add.
D Place the decimal point in the correct location.
PTS: 1 DIF: Average REF: Page 155 OBJ: 3-2.3 Application
NAT: 8.1.3.g TOP: 3-2 Adding and Subtracting Decimals
KEY: addition | decimal | subtraction
ID: A
4
9. ANS: A
Multiply the numbers. The product should have the same number of decimal places as the sum of the decimal
places in the factors.
Feedback
A Correct!
B Place the decimal point in the correct location.
C First, multiply the numbers. Then, place the decimal point in the correct location.
D First, multiply the numbers. Then, place the decimal point in the correct location.
PTS: 1 DIF: Basic REF: Page 160
OBJ: 3-3.1 Multiplying Integers by Decimals NAT: 8.1.3.a
TOP: 3-3 Multiplying Decimals KEY: decimal | integers | multiplication
10. ANS: A
Multiply the numbers. The product should have the same number of decimal places as the sum of the decimal
places in the factors.
Feedback
