Course 1

3-1 Representing, Comparing, and Ordering Decimals3-1

Representing, Comparing, and Ordering Decimals

Course 1

Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Warm UpOrder the numbers from least to greatest.

1. 242, 156, 224, 165

2. 941, 148, 914, 814, 721

3. 345, 376, 354, 397

156, 165, 224, 242

148, 721, 814, 914, 941

345, 354, 376, 397

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Problem of the Day

Lupe is taller than Reba and shorter than Miguel. Tory is shorter than Lupe but taller than Reba. List the four brothers and sisters in order from tallest to shortest.

Miguel, Lupe, Tory, Reba

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Put these decimals in order from largest to smallest. Come up with a rule for ordering.

8.008 8 8.8 8.07 88.1 8.088

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Additional Example 1: Reading and Writing Decimals

Write each decimal in standard form, expanded form, and words.

A. 1.07

B. 0.03 + 0.006 + 0.0009

1 + 0.07Expanded form:

one and seven hundredthsWord form:

0.0369Standard form:

three hundred sixty-nine ten-thousandthsWord form:

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Additional Example 1: Reading and Writing Decimals

Write the decimal in standard form and expanded form.

C. fourteen and eight hundredths

14.08Standard form:

10 + 4 + 0.08Expanded form:

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Check It Out: Example 1

Write each decimal in standard form, expanded form, and words.

A. 1.12

B. 0.6 + 0.008 + 0.0007

1 + 0.1 + 0.02Expanded form:

one and twelve hundredthsWord form:

0.6087Standard form:

six thousand eighty-seven ten-thousandthsWord form:

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Check It Out: Example 1

Write each decimal in standard form and expanded form.

C. eleven and two hundredths

11.02Standard form:

10 + 1 + 0.02Expanded form:

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Additional Example 2: Earth Science Application

The star Wolf 359 has an apparent magnitude of 13.5. Suppose another star has an apparent magnitude of 13.05. Which star has the smaller magnitude?

13.50 Line up the decimal points.

Start from the left and compare the digits.

13.05 Look for the first place where the digits are different.

0 is less than 5.

13.05 < 13.50

The star that has an apparent magnitude of 13.05 has the smaller magnitude.

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Check It Out: Example 2

Tina reported on a star for her science project that has a magnitude of 11.3. Maven reported on another star that has a magnitude of 11.03. Which star has the smaller magnitude?

11.30 Line up the decimal points.

Start from the left and compare the digits.

11.03 Look for the first place where the digits are different.

0 is less than 3.

11.03 < 11.30

The star that has a magnitude of 11.03 has the smaller magnitude.

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Additional Example 3: Comparing and Ordering Decimals

Order the decimals from least to greatest.

16.67, 16.6, 16.07

16.67

16.60

Compare two of the numbers at a time.

Write 16.6 as “16.60.”16.60 < 16.67

16.67

16.07Start at the left and compare the digits.16.07 < 16.67

16.60

16.07Look for the first place where the digits are different.16.07 < 16.60

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3-1 Representing, Comparing, and Ordering Decimals

Additional Example 3 Continued

Graph the numbers on a number line.

16.6716.07 16.6

16 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17

The numbers are ordered when you read the number line from left to right. The numbers in order from least to greatest are 16.07, 16.6, and 16.67.

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Check It Out: Example 3

Order the decimals from least to greatest.

12.42, 12.4, 12.02

12.42

12.40

Compare two of the numbers at a time.

Write 12.4 as “12.40.”12.40 < 12.42

12.42

12.02Start at the left and compare the digits.12.02 < 12.42

12.40

12.02Look for the first place where the digits are different.12.02 < 12.40

Course 1

3-1 Representing, Comparing, and Ordering Decimals

Check It Out: Example 3 Continued

Graph the numbers on a number line.

12.4212.02 12.4

12 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 13

The numbers are ordered when you read the number line from left to right. The numbers in order from least to greatest are 12.02, 12.4, and 12.42.

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3-1 Representing, Comparing, and Ordering Decimals

Lesson Quiz: Part I

Write each in standard form, expanded form and words.

1. 8.0342

2. 10 + 8 + 0.3 + 0.006

3. eight and twelve hundredths

18.306; eighteen and three hundred six thousandths

8 + 0.03 + 0.004 + 0.0002; eight and three hundred forty-two ten thousandths

8.12; 8 + 0.1 + 0.02

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3-1 Representing, Comparing, and Ordering Decimals

Lesson Quiz: Part II

4. It takes Pluto 246.7 years to orbit the Sun, and it

takes Neptune 164.8 years. Which planet takes

longer to orbit the Sun?

5. Order the decimals from least to greatest: 16.35,

16.3, 16.5.

Pluto

16.3, 16.35, 16.5