Name
4.2
?
Number and
Operations—3.4.B
MATHEMATICAL PROCESSES
3.1.C, 3.1.D
Estimate Sums
Essential Question
How can you use compatible numbers and rounding
to estimate sums?
Unlock
Unlock the
the Problem
Problem
The table shows how many dogs went to Pine
Lake Dog Park during the summer months.
About how many dogs went to the park during
June and August?
You can estimate to find about how many or
about how much. An estimate is a number
close to an exact amount.
Pine Lake Dog Park
Month
Number of Dogs
June
432
July
317
August
489
One Way Use compatible numbers.
Compatible numbers are numbers that
are easy to compute mentally and are
close to the real numbers.
432 →
425
+
489 →
__
+
475
__
Math Talk
Mathematical Processes
Will the sum of the
compatible numbers 425
and 475 be greater than
or less than the exact
sum? Explain.
© Houghton Mifflin Harcourt Publishing Company
So, about __ dogs went to Pine Lake
Dog Park during June and August.
1.
What other compatible numbers could you have used?
2.
About how many dogs went to the park during July
and August? What compatible numbers could you
use to estimate?
Module 4
107
Another Way Use place value to round.
432 + 489 =
Math Talk
■
Mathematical Processes
First, find the place to which you want to round.
Round both numbers to the same place. The greatest
place value of 432 and 489 is hundreds. Round each
number to the nearest hundred.
How would you round
432 and 489 to the
nearest ten? What would
be the estimated sum?
Explain.
Find the sum of the rounded numbers.
400 + 500 = _
Share
Share and
and Show
Show
Estimate the sum.
Use compatible numbers.
1.
47
+ 23
_
2.
→
→
Use rounding.
→
304
+ 494
__
+ 25
_
→
300
+
__
Use rounding or compatible numbers to estimate the sum.
3.
6.
421
+
218 +
__
—
4.
267
+
517 +
__
—
7.
369
+
480
__
465
+
478
__
5.
+
—
8.
+
—
27
+ 78
_
+
—
278
+ 369 +
__
—
9.
Multi-Step Green Lawn Service ordered 186 bags of
top soil and 462 bags of fertilizer. Estimate to the nearest
hundred how many bags Green Lawn Service ordered.
Justify your answer.
108
© Houghton Mifflin Harcourt Publishing Company
Problem
Problem Solving
Solving
Name
Problem
Problem Solving
Solving
Use the table for 10–13.
10.
11.
About how many pet bowls were
sold in June and July altogether?
Dan’s Pet Supplies Sold
Pet Bowls
Bags of
Pet Food
June
91
419
July
57
370
August
76
228
Month
What’s the Question?
The answer is about 800.
© Houghton Mifflin Harcourt Publishing Company • Image Credits: ©Image Source/Alamy Images
Write Math
12.
Multi-Step Dan
estimated the lowest monthly sales
of both pet bowls and bags of pet
food to be about 300. What month
had the lowest sales? Explain.
13.
Multi-Step Dan said
the total number of bags of pet food
sold in June, July, and August was
about 1,000. How did Dan estimate?
Explain.
Show Your Work
Module 4 • Lesson 2
109
Mathematical Processes
M
Model ¥ Reason ¥ Communicate
M
Daily
Daily Assessment
Assessment Task
Task
Fill in the bubble for the correct answer choice.
15.
16.
Use Tools The table shows the number of steps
from bottom to top for each pyramid. Which of
these statements shows the best estimate of how
many steps there are in both pyramids?
A
5 + 100 = 105
C
10 + 90 = 100
B
0 + 75 = 75
D
6 + 95 = 101
Pyramid
Djoser
Chichen Itzá
110
6
91
Lea and Josh used sugar cubes to build a model of a
pyramid. First, they glued 196 cubes to make a square
base. Next, they used 144 cubes to make the first step.
Which is the best estimate of the number of sugar cubes
Lea and Josh used to build the first two steps of their
pyramid?
A
440
C
220
B
300
D
400
Multi-Step The height of the Great Pyramid of
Giza is about 481 feet. The length of one side
of its base is 755 feet. What is the best estimate
of the sum of the height and length?
A
1,000 feet
C
1,300 feet
B
1,100 feet
D
1,500 feet
TEXAS Test Prep
17.
Number of Steps
Tracy ordered 325 toys and 165 bags of food for her new
pet store. Which is the best estimate of the total number
of items Tracy ordered?
A
700
C
400
B
500
D
600
© Houghton Mifflin Harcourt Publishing Company • Image Credits: ©Alistair Laming/Alamy
14.
H o mewo rk
and Practice
4.2
Number and Operations—3.4.B
MATHEMATICAL PROCESSES 3.1.C, 3.1.D
Name
Estimate Sums
Use rounding or compatible numbers to estimate the sum.
1.
18 + 53
2.
37 + 52
3.
345 + 223
4.
509 + 478
5.
642 + 212
6.
109 + 688
8.
Elena drove 245 miles last week
and 222 miles this week. She
estimated that she drove about
475 miles in both weeks. How did
Elena estimate?
Problem
Problem Solving
Solving
© Houghton Mifflin Harcourt Publishing Company
7.
Seth bought a pair of sneakers for $48
and a jacket for $64. Explain how you
can estimate to find the total amount
that he spent for the sneakers and
jacket.
Module 4 • Lesson 2 111
TEXAS Test Prep
Lesson
Lesson Check
Check
Fill in the bubble completely to show your answer.
11.
12.
112
Cal has $42. He gets $25 from his
grandparents for his birthday.
Which of these statements shows
the best estimate of the amount of
money Cal has now?
10.
Mr. Avery’s class made $118 for the
fundraiser. Mrs. Bolero’s class made
$189 for the fundraiser. Which of
these statements shows the best
estimate of the total amount both
classes raised?
A
$50 + $30 = $80
B
$50 + $20 = $70
A
$100 + $200 = $300
C
$40 + $40 = $80
B
$125 + $150 = $275
D
$40 + $25 = $65
C
$100 + $100 = $200
D
$200 + $200 = $400
Which is the best estimate of
the total number of students in
kindergarten and first grade at
Wayside Elementary School?
Students at Wayside
Elementary School
Grade
Number of
Students
Kindergarten
187
First Grade
203
Second Grade
382
400
Third Grade
238
500
Fourth Grade
178
A
350
B
300
C
D
Multi-Step Which is the best
estimate of the total number of
students in second, third, and fourth
grade at Wayside Elementary School?
13.
Multi-Step Which is the best
estimate of the total number of
students in all grades at Wayside
Elementary School?
A
500
A
900
B
400
B
1,200
C
700
C
1,100
D
800
D
1,000
© Houghton Mifflin Harcourt Publishing Company
9.