&&66
5HDGDQGZULWHPXOWLGLJLWZKROHQXPEHUVXVLQJEDVHWHQQXPHUDOV
NS 1.1*1%7
Estimate,
round, and manipulate very large (e.g., millions) and
QXPEHUQDPHVDQGH[SDQGHGIRUP&RPSDUHWZRPXOWLGLJLWQXPEHUVEDVHGRQ
very small (e.g., thousandths) numbers.
PHDQLQJVRIWKHGLJLWVLQHDFKSODFHXVLQJ! DQGV\PEROVWRUHFRUGWKHUHVXOWVRI
FRPSDULVRQV
UNDERLYING SKILLS AND CONCEPTS:
place value;
add large numbers
Use Expanded Notation to Estimate
You can use place value and expanded notation to
estimate with large numbers.
E x am p l E
1
Is 4,392 ! 13,535 more or less than 20,000?
Add the digits in the thousands period only.
4 thousand
! 13 thousand
17 thousand
4,000 ! 13,000 " 17,000
Now that’s an
E x am p l E
2
Is 13,629 # 5,975 more or less than 8,000?
13,000 # 5,000 " 8,000
Check the hundreds place.
13,600 and 5,900
13 thousand
# 5 thousand
8 thousand
That’s close.
I’d better check if
the hundreds regroup.
12 thousand
# 5 thousand
7 thousand
600 is less than 900, so you’d regroup.
So the difference is less than 8,000.
page 20
Chapter 2 – Lesson 4
E – © CSL Associates, Inc. All rights reserved.
easy addition problem!
So the sum is less than 20,000.
Name
P RAC T I C E
Circle more or less. Show how you estimated.
1. 25,391 19,079
more or less than 44 thousand?
2. 177,375 3,011
more or less than 120 thousand?
3. 19,575,650 18,625,015
more or less than 40 million?
4. 75,635 25,399
more or less than 50 thousand?
5. 640,935 140,500
more or less than 500 thousand?
6. 25,917,900 9,000,000
more or less than 17 million?
Solve. Explain how you decided.
7. In Bernie’s town there are 1,206,500
adults and 706,900 children.
Do more than 2 million people live in
Bernie’s town?
E – © CSL Associates, Inc. All rights reserved.
Discuss estimation strategies.
no; 1,913,400 people live there.
1,200 thousand 700 thousand
is about 1,900 thousand
Circle the correct choice. Explain how you decided.
8. Which is the best estimate?
A race car costs about 1 million dollars.
A fighter plane costs about 100 million
dollars.
About how much more expensive is a
fighter plane?
Math
Reasoning
A
B
C
D
200 million
101 million
99 million
99
Number Sense
MR 1.1
Solve without paper and pencil.
9. A stadium has 23,415 seats. 2,000 are empty.
How many seats are not empty?
21,415.
Explain how you decided. You can subtract mentally by reducing
the digit in the thousands place by 2.
Chapter 2 – Lesson 4
page 21
MCX94.HW.CL.G5.FM&Lesson.v211
8/2/04
18:02
Page 16
Name
…at home!
P RAC T I C E
Discuss estimation strategies.
1. 35,296 28,089
more or less than 63 thousand?
2. 166,485 4,022
more or less than 170 thousand?
3. 18,628,540 19,575,016
more or less than 40 million?
4. 85,762 35,488
more or less than 50 thousand?
5. 730,825 130,400
more or less than 600 thousand?
6. 35,818,800 9,000,000
more or less than 27 million?
Solve. Explain how you decided.
7. In Jim’s town there are 1,302,500 adults
and 608,800 children.
Do more than 2 million people live in
Jim’s town?
no; 1,302,500 is greater than
1 million. 608,800 is less than
1 million. Round to the hundred
thousands. 300,000 600,000 is 900,000. 1,000,000 900,000 is less than 2 million.
Circle the correct choice. Explain how you decided.
8. Which is the best estimate?
A large home costs about 1 million
dollars. A hotel costs about 100 million
dollars.
About how much more expensive is a
hotel?
Math
Reasoning
A
B
C
D
200 million
101 million
99 million
99
Number Sense
MR 1.1
Solve without paper and pencil.
9. A sports arena has 25,315 seats. 3,000 are empty.
How many seats are not empty?
22,315.
Explain how you decided. You can subtract mentally by reducing
the digit in the thousands place by 3.
page 16
Home Resource and Homework
Chapter 2 Lesson 4
E – © CSL Associates, Inc. All rights reserved.
Circle more or less. Show how you estimated.
MCX94TEG5CH01_32.v7.4.2 2/24/01 19:42 Page 41
Name
P RAC T I C E
Circle more or less. Show how you estimated.
1. 25,391 19,079
more or less than 44 thousand?
2. 177,375 3,011
more or less than 120 thousand?
3. 19,575,650 18,625,015
more or less than 40 million?
4. 75,635 25,399
more or less than 50 thousand?
5. 640,935 140,500
more or less than 500 thousand?
6. 25,917,900 9,000,000
more or less than 17 million?
no; 1,913,400 people live there.
Solve. Explain how you decided.
7. In Bernie’s town there are 1,206,500
adults and 706,900 children.
Do more than 2 million people live in
Bernie’s town?
E – © CSL Associates, Inc. All rights reserved.
Discuss estimation strategies.
1,200 thousand 700 thousand
is about 1,900 thousand
Circle the correct choice. Explain how you decided.
8. Which is the best estimate?
A race car costs about 1 million dollars.
A fighter plane costs about 100 million
dollars.
About how much more expensive is a
fighter plane?
Math
Reasoning
A
B
C
D
200 million
101 million
99 million
99
Number Sense
MR 1.1
Solve without paper and pencil.
9. A stadium has 23,415 seats. 2,000 are empty.
How many seats are not empty?
21,415.
Explain how you decided. You can subtract mentally by reducing
the digit in the thousands place by 2.
Chapter 2 – Lesson 4
Student Book Page
page 21
Name
…at home!
P RAC T I C E
Discuss estimation strategies.
1. 35,296 28,089
more or less than 63 thousand?
2. 166,485 4,022
more or less than 170 thousand?
3. 18,628,540 19,575,016
more or less than 40 million?
4. 85,762 35,488
more or less than 50 thousand?
5. 730,825 130,400
more or less than 600 thousand?
6. 35,818,800 9,000,000
more or less than 27 million?
Solve. Explain how you decided.
7. In Jim’s town there are 1,302,500 adults
and 608,800 children.
Do more than 2 million people live in
Jim’s town?
no; 1,302,500 is greater than
1 million. 608,800 is less than
1 million. Round to the hundred
thousands. 300,000 600,000 is 900,000. 1,000,000 900,000 is less than 2 million.
Circle the correct choice. Explain how you decided.
8. Which is the best estimate?
A large home costs about 1 million
dollars. A hotel costs about 100 million
dollars.
About how much more expensive is a
hotel?
A
B
C
D
200 million
101 million
99 million
99
Number Sense
MR 1.1
Solve without paper and pencil.
9. A sports arena has 25,315 seats. 3,000 are empty.
How many seats are not empty?
22,315.
Explain how you decided. You can subtract mentally by reducing
the digit in the thousands place by 3.
page 16
Home Resource and Homework
Chapter 2 Lesson 4
E – © CSL Associates, Inc. All rights reserved.
Circle more or less. Show how you estimated.