All the solutions provided in **McGraw Hill My Math Grade 5 Answer Key PDF Chapter 5 Lesson 6 Add Decimals **will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 5 Answer Key Chapter 5 Lesson 6 Add Decimals

To add decimals, line up the decimal points and add the digits in the same place-value position.

**Math in My World**

**Example 1**

Mr. Jacobson uses a digital scale to measure 44.2 milligrams of sodium for a chemistry experiment. During the second experiment, he used 33.1 milligrams of sodium. What is the total amount of sodium used?

Find 44.2 + 33.1.

Estimate 44 + 33 = ____________

So, the total amount of sodium used is ___________ milligrams.

Check for Reasonableness

Compare to the estimate, ___________.

__________ ≈ ____________

Answer:

44 + 33 = 77.

the total amount of sodium used is 77.3 milligrams.

77.3 ≈ 77

Explanation:

Compare to the estimate, 77.

77.3 ≈ 77

**Example 2**

Find 19.6 + 4.31.

Estimate 20 + 4 = ____________

So, 19.6 + 4.31 = _____________.

Compare to the estimate, ___________.

__________ ≈ ____________

Answer:

20 + 4 = 24

So, 19.6 + 4.31 = 23.91

Compare to the estimate, 24

23.91 ≈ 24

Explanation:

So, 19.6 + 4.31 = 23.91.

Compare to the estimate, 24

23.91 ≈ 24

**Talk Math**

Explain how annexing zeros might be helpful when adding decimals.

Answer:

First off, annexing zeros means adding an extra zero to assist in mental or written calculations. We have to place the decimal point in the given decimal number point. Now add the same way as we would add the whole numbers. Annex a zero and add the given numbers to find the resultant.

**Guided Practice**

**Add. Check for reasonableness.**

Question 1.

Estimate: 6 + 1 = _____________

So, 6.32 + 1.46 = _____________.

Check for reasonableness

__________ ≈ ____________

Answer:

7, 7.78

7.78 ≈ 7

Explanation:

Estimate: 6 + 1 = 7

So, 6.32 + 1.46 = 7.78.

Check for reasonableness.

7.78 ≈ 7.

Question 2.

Estimate: 1 + 0 = _____________

So, 0.89 + 0.03 = _____________.

Check for reasonableness

__________ ≈ ____________

Answer:

1, 0.92.

Check for reasonableness

0.92 ≈ 1

Explanation:

Estimate: 1 + 0 = 1

So, 0.89 + 0.03 = 0.92.

Check for reasonableness

0.92 ≈ 1

**Independent Practice**

**Add. Check for reasonableness.**

Question 3.

Answer:

8.34

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 8.34.

Question 4.

Answer:

25.06

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 25.06.

Question 5.

Answer:

33.46

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 33.46.

Question 6.

Answer:

46.98

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 46.98.

Question 7.

Answer:

1.02

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 1.02.

Question 8.

Answer:

11.19

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 11.19.

Question 9.

6.57 + 1.2 = ____________

Answer:

7.77

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 7.77.

Question 10.

19.21 + 11.03 = ____________

Answer:

30.24

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 30.24

Question 11.

3.08 + 1.64 = _____________

Answer:

4.72

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed. Hence the answer is 4.72.

**Algebra Find each unknown.**

Question 12.

8.9 + 0.15 = x

x = _____________

Answer:

9.05

Explanation:

Given,

8.9 + 0.15 = x

Now find the value of x.

Add both numbers.

8.9 + 0.15 = 9.05

Question 13.

42.2 + 7.69 = d

d = _____________

Answer:

49.89

Explanation:

Given,

42.2 + 7.69 = d

find the value of d

add both numbers

The answer is 49.89.

Question 14.

5.63 + 1.22 = w

w = ______________

Answer:

w = 6.85

Explanation:

Given,

5.63 + 1.22 = w

find the value of w.

add the numbers

6.85

**Problem Solving**

Question 15.

Horacio bought a logic puzzle and batteries from a toy store. Use the table at the right to find the total cost of the two items, not including tax.

Answer:

$25.34

Explanation:

Given,

Cost of logic puzzle = 14.95

Cost of batteries = 10.39

cost of carrying case = 12.73

Total cost = 14.95 + 10.39 = $25.34

Question 16.

An athlete training for the Olympics swims each lap of a four-lap race in the following times: 54.73, 54.56, 54.32, and 54.54 seconds. What is the total time it takes her to swim the four laps?

Answer:

218.55

Explanation:

Given,

An athlete training for the Olympics swims each lap of a four-lap race in the following times: 54.73, 54.56, 54.32, and 54.54 seconds.

Now add them

54.73 + 54.56 + 54.32 + 54.54 = 218.55

Total time = 218.55seconds

Question 17.

Terrance is bicycling on a trail. He bicycles for 12.6 miles and takes a break. Then he bicycles for 10.7 miles. How many miles has Terrance bicycled in all?

Answer:

23.3 miles

Explanation:

Terrance bicycles for 12.6 miles and takes a break.

After the break, he bicycles for 10.7 miles.

Total miles = 12.6 + 10.7 = 23.3 miles

Terrance bicycled 23.3 miles.

**HOT Problems**

Question 18.

**Mathematical PRACTICE** Make a Plan Write a real-world word problem that can be solved by adding 34.99 and 5.79. Then solve.

Answer:

Mr. Rasool spent $34.99 on paper and $5.79 on pencils at the store. How much he spent in all?

The answer is $40.78.

Explanation:

We had written a real-world word problem that can be solved by adding 34.99 and 5.79. Now solve the problem.

$34.99 + $5.79 = $40.78

Question 19.

**Mathematical PRACTICE** Use Number Sense Write two different pairs of decimals whose sums are 8.69. One pair should involve regrouping.

Answer:

The pairs are without regrouping: 4.29 + 4.4

With regrouping 5.72 + 2.97

Explanation:

From the given information,

We can write two different pairs of decimals whose sums are 8.69.

We can take any two numbers who sum is 8.69.

Let us assume first number is 4.29 then the second number is 4.4.

Now let us check this by adding the numbers

4.29 + 4.4 = 8.69

The next pair should involve regrouping.

The first number be 5.72 and the second number will be 2.97

We can check this by adding the numbers

5.72 + 2.97 = 8.69

Hence the pairs are without regrouping 4.29 + 4.4 and with regrouping 5.72 + 2.97.

Question 20.

**Building on the Essential Question** How does place value help you add decimals?

Answer:

whenever we are adding decimals, we must first line up all the decimal points in a column. Lining up the decimal points means that each digit is in the proper place-value. We can add the digits by using the same place value position to find the required sum.

### McGraw Hill My Math Grade 5 Chapter 5 Lesson 6 My Homework Answer Key

**Practice**

**Add. Check for reasonableness.**

Question 1.

Answer:

6.55

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed.

Question 2.

Answer:

12.17

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed.

Question 3.

Answer:

29.75

Explanation:

1. First write the digits in a vertical column, and align the decimal points.

2. Add each column starting from the right and working left. Carry digits when needed.

**Problem Solving**

Question 4.

Devin has a new cell phone that holds 1.5 gigabytes of memory for music. He has already used 1.35 gigabytes of the memory. Will he have enough space to download a song that will use 0.12 gigabyte of memory? Explain.

Answer:

Yes. He has enough space to download a song that will use 0.12 gigabytes of memory.

Explanation:

Devin has a new cell phone that holds 1.5 gigabytes of memory for music.

He has already used 1.35 gigabytes of memory.

1.35 + 0.12 = 1.47

1.47 > 1.5

Question 5.

A large bag of sand weighs 48.5 pounds. A small bag of sand weighs 24.6 pounds. If Mrs. Waggoner buys a large bag and a small bag, how many pounds of sand did she purchase altogether?

Answer:

73.1 pounds.

Explanation:

Given,

A large bag of sand weighs 48.5 pounds.

A small bag of sand weighs 24.6 pounds.

Total pounds = 48.5 + 24.6 = 73.1 pounds.

Question 6.

**Mathematical PRACTICE** Explain to a Friend Grady wants to buy a basketball video game that costs $59.95, including tax. He has $45.50 in cash and a gift certificate for $15.25. Is that enough to buy the video game? Explain to a friend.

Answer:

$60.75.

Yes, he has enough. Grady can buy the game and we will have 80 cents to spare.

Explanation:

Cost of video game = $59.95,

He has $45.50 in cash and a gift certificate for $15.25.

$45.50 + $15.25 = $60.75

$60.75 – $59.95 = $00.80 = 80 cents.

Question 7.

**Mathematical PRACTICE** Identify Structure Lakshmi wants to start saving coins in a piggy bank. Her mother gave her three quarters and two pennies on Monday and two dimes and one nickel on Tuesday. Fill in the amounts of money that Lakshmi’s mother gave her in the space provided on the bar diagram below.

Answer:

Explanation:

Given,

3 quarters and 2 pennies

1 quarter = 25 cents 1 penny = 1 cent

Monday = 3 × 25 = 75 + 2 = 77 cents = $0.77 cents

2 dimes and one nickel on Tuesday

1 dime = 10 cents and 1 nickel = 5 cents

2 × 10 + 1 × 5 = 20 + 5 = 25 cents = $0.25 cents

Total 77 + 25 = 102 cents = $1.02

**Test Practice**

Question 8.

Marcus entered a race that involves swimming and running. He will need to swim 0.72 mile and run 1.65 miles. How far will Marcus travel in all during the race?

(A) 2.37 miles

(B) 2.17 miles

(C) 2.07 miles

(D) 1.37 miles

Answer:

2.37 miles

Explanation:

Given,

Marcus needs to swim = 0.72 miles

Marcus needs to run = 1.65 miles

Total = 1.65 + 0.72 = 2.37 miles

Marcus traveled in all during the race is 2.37 miles.