All the solutions provided in McGraw Hill Math Grade 4 Answer Key PDF Chapter 2 Lesson 3 Add and Subtract Mentally will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 4 Answer Key Chapter 2 Lesson 3 Add and Subtract Mentally
To mentally add or subtract larger numbers, you can take and give to make one number end in a ten, hundred, or thousand.
Math in My World
Example 1
The table shows the number of instruments sold at an instrument store. What is the total number of guitars and trumpets that was sold?
Find 223 + ____
Make a ten.
So, there were 290 guitars and trumpets sold.
Example 2
Find 184 – 59.
Make a ten. 59 is close to 60.
184 – 59 = 125.
Example 3
Attendance at a concert was 82,000 people. The following week, there were 76,000 people. How many more people attended the concert the first week?
Find 82,000 – 76,000.
Both numbers have the same greatest place-value position.
Helpful Hint
You can also think
82 thousands – 76 thousands = ____ thousands.
1 First subtract the ten thousands and the thousands.
82 – 76 = 6
So, 6 thousand more people attended the first concert.
2 The difference, 6, is in the thousands place.
So, 82,000 — 76,000 = 6,000
Talk Math
Look at Exercise 3. Explain why you added 4 to the difference of 104 before writing the final answer.
Answer : Since we subtracted extra 4 add it back in , then
104 + 4 = 108
Explanation:
184 – 76
Make a ten. Add 4 to 76
76 + 4 = 80
184 – 80 = 104
Since we subtracted extra 4 add it back in , then
104 + 4 = 108
So, 184 – 76 = 108
Guided Practice
Make a ten, hundred, or thousand to mentally add.
Question 1.
So, 57 + 58 = ____
Answer: 57 + 58 = 115
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 57 as 55 by subtracting 2 and 58 as 60 by adding 2
That will be 55 + 60 = 115
Question 2.
So, 499 + 77 = ____
Answer: 499 + 77 = 576
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 77 as 76 by subtracting 1 and 499 as 500 by adding 1
That will be 500 + 76 = 576
Use mental math to subtract.
Question 3.
184 – 76
Make a ten. 76 + 4 = ____
184 – ___ = ____
104 + 4 = ____
So, 184 – 76 = ____
Answer: 184 – 76 = 108
Explanation:
184 – 76
Make a ten. Add 4 to 76
76 + 4 = 80
184 – 80 = 104
Since we subtracted extra 4 add it back in , then
104 + 4 = 108
So, 184 – 76 = 108
Independent Practice
Question 4.
8,825 – 6,397
Make a hundred.
6,397 + 3 = ___
____ – 6,400 = ____
2,425 + 3 = ____
So, 8,825 — 6,397 = ____
Answer: 8,825 — 6,397 = 2,428
Explanation:
Make a hundred.
6,397 + 3 = 6,400
8,825 – 6,400 = 2,425
Since we subtracted extra 3 add it back in , then
2,425 + 3 = 2,428
So, 8,825 — 6,397 = 2,428
Question 5.
684 – 169
Make a ten.
169 + 1 = ___
___ – 170 = ____
514 + 1 = ____
So, 684 – 169 = ____
Answer: 684 – 169 = 515
Explanation:
684 – 169
Make a ten.
169 + 1 = 170
684 – 170 = 514
Since we subtracted extra 1 add it back in , then
514 + 1 = 515
So, 684 – 169 =515
Make a ten, hundred, or thousand to mentally add.
Question 6.
738 + 56 = ___
Answer: 738 + 56 = 794
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 738 as 734 by subtracting 4 and 56 as 60 by adding 4
That will be 734 + 60 = 794
So, 738 + 56 = 794
Question 7.
223 + 728 = ____
Answer: 223 + 728 = 951
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 223 as 221 by subtracting 2 and 728 as 730 by adding 2
That will be 221 + 730 = 951
So, 223 + 728 = 951
Question 8.
6,627 + 3,315 = ___
Answer: 6,627 + 3,315 = 9,942
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 3,315 as 3,312 by subtracting 3 and 6,627 as 6,630 by adding 3
That will be 6,630 + 3,312 = 9,942
So, 6,627 + 3,315 = 9,942
Question 9.
5,478 + 1,312 = ____
Answer: 5,478 + 1,312 = 6,790
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 1,312 as 1,310 by subtracting 2 and 5,478 as 5,480 by adding 2
That will be 5,480 + 1,310 = 6,790
So, 5,478 + 1,312 = 6,790
Use mental math to subtract.
Question 10.
7,930 – 4,623 = ___
Answer: 7,930 – 4,623 = 3,307
Explanation:
Make a ten.
4,623 + 7 = 4,630
7,930 – 4,630 = 3,300
Since we subtracted extra 7 add it back in , then
3,300 + 7 = 3,300
So, 7,930 – 4,623 = 3,307
Question 11.
5,547 – 2,539 = ____
Answer: 5,547 – 2,539 = 3,008
Explanation:
Make a ten.
2,539 + 1 = 2,540
5,547 – 2,540 = 3,007
Since we subtracted extra 1 add it back in , then
3,007 + 1 = 3,008
So, 5,547 – 2,539 = 3,008
Question 12.
8,329 – 7,218 = ____
Answer: 8,329 – 7,218 = 1,111
Explanation:
Make a ten.
8,329 + 1 = 8,330
8,330 – 7,218 = 1,110
Since we subtracted extra 1 add it back in , then
1,110 + 1 = 1,111
So, 8,329 – 7,218 = 1,111
Question 13.
3,273 – 1,256 = ____
Answer: 3,273 – 1,256 = 2,017
Explanation:
Make a ten.
1,256 + 4 = 1,260
3,273 – 1,260 = 2,013
Since we subtracted extra 4 add it back in , then
2,013 + 4 = 2,017
So, 3,273 – 1,256 = 2,017
Subtract. Draw a line to the difference in the second column.
Answer:
Problem Solving
Use mental addition or subtraction to solve.
Question 18.
Attendance at a concert was 12,769. The following evening, the attendance was 13,789. How many more people attended the concert on the second night?
Answer: 1,020 more people attended the concert on the second night.
Explanation:
Given, Attendance at a concert was 12,769.
The following evening, the attendance was 13,789.
13,789 – 12,769 = ?
Make a ten.
12,769 + 1 = 12,770
13,789 – 12,770 = 1,019
Since we subtracted extra 1 add it back in , then
1,019 + 1 = 1,020
So, 13,789 – 12,769 = 1,020
Thus, 1,020 more people attended the concert on the second night.
Question 19.
Mathematical PRACTICE 2 Reason Yolanda is finding 23,567 – 12,458. She added 2 to 12,458 before subtracting. Then she added it in again after she subtracted. Is her method correct? Explain.
Answer: yes
Explanation:
Given, 23,567 – 12,458.
Make a ten.
12,458 + 2 = 12,460
23,567 – 12,460 = 11,107
Since we subtracted extra 2 add it back in , then
11,107 + 2 = 11,109
So, 23,567 – 12,458 = 11,109
HOT Problems
Question 20.
Mathematical PRACTICE 1 Make Sense of Problems Mentally add or subtract to get to the finish line.
Answer:
Question 21.
? Building on the Essential Question Why is mental addition and subtraction important when you learn more difficult concepts?
Answer: You can simplify mental math for the addition of two digit numbers by treating the digit separately. You can also treat the digit separately in subtraction if the number subtracted has both digit smaller. And we can also simply subtraction by adding the same number to both terms.
Learning different strategies will help them see different ways to solve problems and students will gravitate to the way that best meets where they’re at.
McGraw Hill My Math Grade 4 Chapter 2 Lesson 3 My Homework Answer Key
Make a ten, hundred, or thousand to mentally add.
Question 1.
118 + 203 = ___
Answer: 118 + 203 = 321
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 203 as 201 by subtracting 2 and 118 as 120 by adding 2
That will be 201 + 120 = 321
So, 118 + 203 = 321
Question 2.
549 + 24 = ____
Answer: 549 + 24 = 597
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 24 as 23 by subtracting 1 and 549 as 550 by adding 1
That will be 550 + 23 = 597
So, 549 + 24 = 597
Question 3.
1,198 + 46 = ___
Answer: 1,198 + 46 = 1,244
Explanation:
To make a hundred ,
Take from one addend and give to the other addend , that is make 46 as 44 by subtracting 1 and 1,198 as 1,200 by adding 2
That will be 1,200 + 44 = 1,244
So, 1,198 + 46 = 1,244 .
Question 4.
745 + 997 = ____
Answer: 745 + 997 = 1,742
Explanation:
To make a ten ,
Take from one addend and give to the other addend , that is make 745 as 742 by subtracting 3 and 997 as 1000 by adding 3
That will be 1,000 + 742 = 1,742
So, 745 + 997 = 1,742 .
Use mental math to subtract.
Question 5.
982 – 56 = ___
Answer: 982 – 56 = 926
Explanation:
Make a ten.
56 + 4 = 60
982 – 60 = 922
Since we subtracted extra 4 add it back in , then
922 + 4 = 926
So, 982 – 56 = 926
Question 6.
7,499 — 4,100 = ____
Answer: 7,499 — 4,100 = 3,399
Explanation:
Make a hundred.
7,499 + 1 = 7,500
7,500 – 4,100 = 3,398
Since we subtracted extra 4 add it back in , then
3,398 + 1 = 3,399
So, 7,499 — 4,100 = 3,399
Problem Solving
Use mental math to solve.
Question 7.
The cafeteria sells 498 cartons of milk and 246 bottles of juice every day. How many total milk and juice containers are sold each day?
Answer: Totally, 744 milk and juice containers are sold each day
Explanation:
Given, 498 + 246
Make a ten
Take from one addend and give to the other addend , that is make 246 as 244 by subtracting 2 and 498 as 500 by adding 2
That will be 500 + 244 = 744
So, 498 + 246 = 744
So, 744 milk and juice containers are sold each day
Question8.
Mathematical PRACTICE 5 Use Math Tools Terrell had a chain of 56 paper clips. Some of the paper clips fell off. Now there are 38 paper clips in the chain. How many fell off?
Answer: 18 clips fell off from the chain
Explanation:
Given, 56 -38
Make a ten.
38 + 2 = 40
56 – 40 = 16
Since we subtracted extra 2 add it back in , then
16 + 2 = 18
So, 56 – 38 = 18
Hence, 18 clips fell off from the chain
Question 9.
Li counts 203 stars in the sky. The next night, she counts 178 stars. How many stars in all did she see on the two nights?
Answer: She saw 381 stars on the two nights
Explanation:
Given, 203 + 178
To make a ten ,
Take from one addend and give to the other addend , that is make 203 as 201 by subtracting 2 and 178 as 180 by adding 2
That will be 201 + 180 = 381
So, 203 + 178 = 381
She saw 381 stars on the two nights.
Question 10.
There were 132 children at the museum on Saturday. On Sunday, there were 61 children. How many children were there on Saturday and Sunday?
Answer: There are 193 children at the museum on Saturday and Sunday
Explanation:
Given, 132 + 61
To make a ten ,
Take from one addend and give to the other addend , that is make 61 as 60 by subtracting 1 and 132 as 133 by adding 1
That will be 133 + 60 = 193
So, 132 + 61 = 193
There are 193 children at the museum on Saturday and Sunday
Test Practice
Question 11.
Mikah’s dog has 39 spots. Jonelle’s dog has 85 spots. How many more spots does Jonelle’s dog have?
A. 45 spots
B. 46 spots
C. 41 spots
D. 44 spots
Answer: B
Explanation:
Given, Mikah’s dog has 39 spots.
Jonelle’s dog has 85 spots.
85 – 39
Make a ten.
39 + 1 = 40
85 – 40 = 45
Since we subtracted extra 1 add it back in , then
45 + 1 = 46
So, 85 – 39 = 46
There are 46 more spots on Jonelle’s dog .