21 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed.
Practice 1 Adding Decimals
Fill in the blanks. Write each sum as a decimal.
Adding and
Subtracting Decimals
Ch
apt
er 0.3 1 0.5 5 tenths 1 tenths 5 tenths 5 1. 0.8 1 0.2 5 tenths 1 tenths 5 tenths 5 2. 0.7 1 0.7 5 tenths 1 tenths 5 tenths 5 3. 0.9 1 0.8 5 tenths 1 tenths 5 tenths 5 Lesson 8.1 AddingDecimals Example5
3
8
0.8
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 22
Fill in the blanks. 4.
4 . 8 1 3 . 6 Add the tenths.
8 tenths 1 6 tenths 5 tenths
Regroup the tenths.
tenths 5 one and tenths
4 . 8 1 3 . 6 Add the ones.
4 ones 1 3 ones 1 one 5 ones
So, 4.8 1 3.6 5 .
Add.
5. 8 . 5
1 2 . 3 6. 1 1 . 66 . 6
Write in vertical form. Then add.
7. 15.7 1 3.8 5 8. 22.9 1 7.2 5
Step 1
Step 2
Line up the decimal points.
23 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed.
Practice 2 Adding Decimals
Fill in the blanks. Write each sum as a decimal.
0.02 1 0.04 5 hundredths 1 hundredths 5 hundredths 5 1. 0.03 1 0.07 5 hundredths 1 hundredths 5 hundredths 5 2. 0.06 1 0.08 5 hundredths 1 hundredths 5 hundredths 5 3. 0.09 1 0.05 5 hundredths 1 hundredths 5 hundredths 5 Lesson 8.1 AddingDecimals Example
2
4
6
0.06
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 24
Fill in the blanks. 4.
2 . 3 4 1 0 . 8 7
Add the hundredths.
4 hundredths 1 7 hundredths
5 hundredths
Regroup the hundredths.
hundredths 5 tenth hundredth
2 . 3 4 1 0 . 8 7 Add the tenths.
3 tenths 1 8 tenths 1 tenth 5 tenths
Regroup the tenths.
tenths 5 one and tenths
2 . 3 4 1 0 . 8 7 Add the ones.
2 ones 1 0 ones 1 one 5 ones
So, 2.34 1 0.87 5 .
Line up the decimal points.
Step 1
Step 2
25 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. Lesson 8.1 AddingDecimals Add. 5. 0 . 0 2 1 0 . 3 5 6. 1 0 . 4 60 . 0 6
Write in vertical form. Then add.
7. $0.57 1 $0.29 5 $
8. 3.6 1 0.54 5
9. $0.78 1 $0.88 5 $
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 26 Chapter8 Addingand Subtracting Decimals
Derek hops two steps on each number line. Which decimal does he land on?
Write the correct decimal in each box.
1.0 0 2.0 3.0 4.0 0.9 2.42 11. 11.0 10.0 12.0 13.0 14.0 1.26 2.57 12. 50.0 51.0 52.0 53.0 54.0 55.0 2.69 1.83 13. 1.0 1.2 1.4 1.6 1.8 2.0 0.36 0.38 Example
3.32
27 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed.
Practice 3 Subtracting Decimals
Fill in the blanks. Write each difference as a decimal.
0.9 2 0.4 5 tenths 2 tenths 5 tenths 5 1. 1 2 0.3 5 tenths 2 tenths 5 tenths 5 2. 1.3 2 0.6 5 tenths 2 tenths 5 tenths 5 3. 1.8 2 0.9 5 tenths 2 tenths 5 tenths 5 Lesson 8.2 SubtractingDecimals Example
9
4
5
0.5
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 28 Chapter8 Addingand Subtracting Decimals
Fill in the blanks. 4.
3 . 5 2 1 . 7
You cannot subtract 7 tenths from 5 tenths. So, regroup 3 ones and 5 tenths.
3 ones and 5 tenths
5 ones and tenths
Subtract the tenths.
tenths 2 7 tenths 5 tenths
3 . 5 2 1 . 7
Subtract the ones.
ones 2 one
5 one
So, 3.5 2 1.7 5 .
Step 1
29 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. Lesson 8.2 SubtractingDecimals Subtract. 5. 4 . 6 2 2 . 2 6. 7 . 4 2 6 . 5
Write in vertical form. Then subtract.
7. 6.7 2 2.4 5 8. 3 2 1.3 5
Fill in the blanks. Write each difference as a decimal.
0.08 2 0.02 5 hundredths 2 hundredths 5 hundredths 5 9. 0.23 2 0.19 5 hundredths 2 hundredths 5 hundredths 5 10. 0.1 2 0.06 5 hundredths 2 hundredths 5 hundredths 5
8
2
6
0.06
ExampleChapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 30
Fill in the blanks. 11.
4 . 2 3 2 1 . 5 4
You cannot subtract 4 hundredths from 3 hundredths. So, regroup 2 tenths 3 hundredths.
2 tenths 3 hundredths
5 tenth hundredths
Subtract the hundredths.
hundredths 2 hundredths
5 hundredths
Step 2
4 . 2 3 2 1 . 5 4
You cannot subtract 5 tenths from tenth.
So, regroup 4 ones and tenth.
4 ones and tenth
5 ones and tenths
Subtract the tenths.
tenths 2 5 tenths 5 tenths
31 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. Lesson 8.2 SubtractingDecimals Step 3 4 . 2 3 2 1 . 5 4 Subtract the ones.
ones 2 1 one 5 ones
So, 4.23 2 1.54 5 . Subtract. 12. 0 . 3 9 2 0 . 0 7 13. 0 . 5 1 2 0 . 3 6 14. 2 . 3 5 2 0 . 4 8 15. 1 2 . 4 5 2 1 0 . 6 3 16. 1 0 . 1 3 2 7 . 1 8 17. 2 0 2 1 4 . 5 6
32 Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed.
Write in vertical form. Then subtract.
18. 5.38 2 2.73 5
19. 1.06 2 0.38 5
20. 5.6 2 1.72 5
33 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. Lesson 8.3 Real-WorldProblems: Decimals
Practice 4 Real-World Problems: Decimals
Solve. Show your work.
1 pound of grapes costs $1.79 and 1 pound of peaches costs $1.49. What is the total cost of 1 pound of grapes and 1 pound of peaches?
1. A tank is full of water. After 16.5 liters of water are used,
8.75 liters of water are left. How much water was in the full tank?
2. A piece of fabric is 4.5 yards long. A customer buys 2.35 yards of the fabric. How many yards of fabric are left?
3. Mr. Larson lives 8.7 miles from school. He was driving home from school and stopped 3.5 miles along the way at a supermarket. How much farther does he have to drive before he reaches home?
Example
Cost of grapes + cost of peaches = total cost
$1.79 + $1.49 = $3.28
The total cost of 1 pound of grapes
and 1 pound of peaches is $3.28.
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 34
4. A grocery store is having a sale. A loaf of wheat bread regularly costs $2.29, but the sale price is $1.79.
The store is also offering 50c/ off on a gallon of fresh milk. If Mrs. Larson buys a gallon of fresh milk and a loaf
of wheat bread, how much does she save on her purchases?
5. Lily bought a skirt for $25.90 and a shirt for $19.50.
She paid the cashier $50. How much change did she receive?
6. Shannon collects rainwater to water her flowers. She has one bucket with 3.4 gallons of water and another with 1.85 gallons less. She uses both buckets to water the flowers. How many gallons of water does she use?
35 © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. Chapter8 Adding andSubtractingDecimals
1. Miguel subtracts two numbers and gets the answer 4.95. The lesser of the two numbers is 3.4.
What is the other number?
2. Julia subtracts two numbers and gets the answer 6.8. The greater of the two numbers is 10.55.
What is the other number?
Challenging Practice
Chapter8 Addingand Subtracting Decimals © M arshal l Ca vendish In terna tional (Singapor e) Priv at e Limit ed. 36 Chapter8 Addingand Subtracting Decimals
1. The number in each rectangle is the sum of the numbers in the two circles next to it. Find the numbers in the circles.
A
B C
1.7
0.9 1.4
2. Each week, Rena saves $5. Her brother saves $2.50 less each week, but he started saving 4 weeks earlier. After how many weeks will Rena’s savings be equal to her brother’s?
