Lesson
1
Place Value in Whole Numbers
Problem Solving:
Reading Word Problems Carefully
Place Value in Whole Numbers
Vocabulary
How does a digit get its value?
We can write any number using the digits 0 through 9. The digits of
a number have different values based on their position in the number.
This is called the place value of the digit.
digits
place value
place-value chart
We can use a place-value chart to help determine the value of each
digit in a number.
Digits
Place-Value Chart
4
4
7
8
8
9
Digits are numbers
from 0 through 9.
One
s
Ones
Ten
s
place value
Thousands
Hu
millndred
ions
T
mill en
ions
Mill
ions
H
thoundred
u sa
nds
T
tho en
u sa
nds
Tho
u sa
nds
Hun
dre
ds
Millions
7
Place Value
9
digits
4
7
8
9
Place Value of a digit
is a value or position
in the number.
Unit 1 • Lesson 1 3
Lesson 1
How does the position of the digit affect
its value?
The value of a digit and its position in the place-value chart are related.
Look at the example below.
Example 1
Find the value of the digits.
Look carefully at the number 285 in the place-value chart:
4
72
8
One
s
Ones
Ten
s
Thousands
Hu
millndred
ions
T
mill en
ions
Mill
ions
H
thoundred
u sa
nds
T
tho en
u sa
nds
Tho
u sa
nds
Hun
dre
ds
Millions
95
In the number 285, the digit 2 is in the hundreds place.
The 2 has a value of 2 hundreds, or 200.
Now look at the number 25,981 in the place-value chart:
2
4
5
7
9
8
One
s
Ones
Ten
s
Thousands
Hu
millndred
ions
T
mill en
ions
Mill
ions
H
thoundred
u sa
nds
T
tho en
u sa
nds
Tho
u sa
nds
Hun
dre
ds
Millions
9
1
In the number 25,981, the digit 2 is in the ten thousands place.
The 2 has a value of 2 ten thousands, or 20,000.
The digit 2 is farther to the left in 25,981 than in 285.
The place value of the digit 2 is greater in 25,981 than in 285.
4 Unit 1 • Lesson 1
Lesson 1
How do we read and write numbers?
When we read and write numbers, we separate them into groups of
three digits.
To read a number, we say the one-, two-, or three-digit number
for each group, and then we say the name of the group.
Example 1
Read the number in the place-value chart.
7
6
4
43
71
83
One
s
Ones
Ten
s
Thousands
Hu
millndred
ions
T
mill en
ions
Mill
ions
H
thoundred
u sa
nds
tho Ten
u sa
nds
Tho
u sa
nds
Hun
dre
ds
Millions
98
We read the number in the place-value chart as
7 million, 643 thousand, 138. We do not need to say 138 ones.
To write a number, separate each group with a comma. Start with the
ones digit, and place a comma after every three digits.
The number in the place-value chart above is written 7,643,138.
Improve Your Skills
How would we write five thousand forty-one?
Common mistakes:
five hundred forty-one
541
500,041five hundred thousand forty-one
5,000,401five million four hundred one
We can avoid these mistakes
if we use place value.
The correct way to write the number is 5,041.
Unit 1 • Lesson 1 5
Lesson 1
How does the greatest place value of a number
relate to the number of digits in that number?
Thinking about the greatest place value in a number helps us write the
correct number of digits for that number.
Improve Your Skills
Marvin’s teacher asked him to write the number
six hundred thousand five hundred nine.
Marvin wrote the number like this: 60,509.
ERROR
The table shows that any number in the hundred thousands has
6 digits. The number Marvin wrote only has 5 digits, so we know
he is incorrect.
Greatest Place Value
Ones
Tens
Hundreds
Thousands
Ten thousands
Hundred thousands
Millions
Ten millions
Hundred millions
Number of Digits
1 digit
2 digits
3 digits
4 digits
5 digits
6 digits
7 digits
8 digits
9 digits
Example
5
35
135
4,135
54,135
654,135
2,654,135
82,654,135
782,654,135
We correctly write the number as 600,509.
Apply Skills
Turn to Interactive Text,
page 2.
6 Unit 1 • Lesson 1
Reinforce Understanding
Use the mBook Study Guide
to review lesson concepts.
Lesson 1
Problem Solving: Reading Word Problems Carefully
What are the first steps in solving word
problems?
Solving word problems can be difficult. There can be a lot of information
to read. Before solving any problem, we must read it carefully.
To begin solving a word problem, we should:
• Figure out what the problem is asking.
• Rewrite what the question is or what the problem is asking.
Example 1
Solve the word problem.
Problem:
There are 64 teams in the first round of a college basketball
tournament. There are 4 divisions with an equal number of teams in
each division. Each team plays until they lose a game. There are 2
teams in the finals. How many teams are in each division in the first
round of the basketball tournament?
• Figure out what the problem is asking.
The last sentence tells us what the problem is asking.
• Rewrite the question or what the problem asks.
How many teams are in each division in the first round of the
basketball tournament?
Problem-Solving Activity
Turn to Interactive Text,
page 4.
Remember to read the
problem carefully before
beginning to solve it.
Reinforce Understanding
Use the mBook Study Guide
to review lesson concepts.
Unit 1 • Lesson 1 7
Lesson 1
Homework
Activity 1
Write the value of the digit.
ModelIn the number 4,237,001, what is the value of the 7? Answer: 7,000
1.
In the number 12,005,999, what is the value of the 2?
2.
In the number 3,567, what is the value of the 7?
3.
In the number 16,295,001, what is the value of the 9?
4.
In the number 27,095, what is the value of the 0?
5.
In the number 632,981,075, what is the value of the 1?
Activity 2
Write the value of the digit that is underlined.
Model45,079 Answer: 5,000
1.
10,119
2.
5,092
3.
29,010
4.
5,376
5.
129,020
6.
3,506,999
7.
62,125
8.
25,000,210
9.
529,023,311
Activity 3
The number is written in words.
Write how many digits the number has.
Then write the number.
Digits?
Modelseven thousand twelve
4 digits
1.
sixty five thousand twenty-nine
2.
seventy four thousand one hundred sixty
3.
eight hundred thirteen
4.
four million twenty-five
Number
7,012
Activity 4 • Distributed Practice
Add. Try to find the sum mentally.
8 1.
8+3
2.
5+2
3.
9+4
4.
7+8
5.
8+0
6.
1+5
7.
6+4
8.
7+7
Unit 1 • Lesson 1