Decimals and Place Value & Comparing

Decimals

Lessons 3.1 & 3.3

Decimals & Place Value

• Where do you see decimals?

MoneyTimes (races)Scores

• We will look at how to write decimal amounts in words, numbers, or using models.

Decimals & Place ValuePlace Value Chart

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Decimals & Place Value

Example 1 – Write the following amount in word form.

18.021

Eighteen and twenty-one

Lowest place value?thousandths

thousandths

Your Turn

Question #1 – Write the following amount as a decimal.

Ninety and one-hundred nine thousandths

90.109

Your Turn

Question #2 – Write the following amount as a decimal.

Seventy-two and seven hundredths

72.07

Comparing Decimals

• Comparing decimals (greater than, less than, or equal to) is similar to comparing whole numbers.

• Special attention must be given to place value to compare decimals.

Comparing Decimals• To compare/order decimals:

1st - line up the decimal points.2nd – start from the highest place value, move right and find where the digits are different.3rd - Compare these digits (>, <, or =)

Comparing Decimals

Example 2Compare the following numbers:

71.264 ___ 71.354A. >

B. <

C. =

71.264

71.354

<

71.2 71.371.25 71.35

Your TurnQuestion #3Allison has $125.08. Greg has $125.06.

Compare the two amounts of money. Who has the most money?

125.08

125.06A. Allison

B. Greg

Allison has the most money.

Your TurnQuestion #4Compare the following numbers:

123.18 ____ 123.1800

123.18

123.1800

A. >

B. <

C. =

Equivalent Decimals• Equivalent decimals are decimals

that name the same number (such as 281.07 and 281.0700), or they are equal.

• Annexing means to add zeros after the last non-zero digit in a decimal. These zeros are placeholders.

Comparing DecimalsExample 3Order the following numbers from least to

greatest:9.41 9.399 9.4102 9.4110

9.4100

9.3990

9.4102

9.4110The order of the numbers from least to greatest is

9.399, 9.41, 9.4102, 9.4110

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Your TurnQuestion #5A dance competition is held where the

group with the highest score wins. Place the following scores in order from greatest to least to determine which team wins the competition.

Dance Scores

Team A Team B Team C Team D

94.175 94.05 96.35 94.15

Your Turn

Question #5 (answer choices)

A) Team A, Team B, Team C, Team DB) Team B, Team C, Team A, Team DC) Team C, Team A, Team D, Team BD) Team D, Team B, Team A, Team C

Your TurnQuestion #5 (procedure to follow)

96.35 (Team C), 94.175 (Team A), 94.15 (Team D), 94.05 (Team B)

Team A 94.175Team B 94.050Team C 96.350Team D 94.150

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Team C wins the dance competition.

Independent Practice Time

Please put the following numbers in order

1.4, 1.04, 1.004, 1.007, 1.7, .07

And then these

• MA.A.1.3.1.6.1 – knows word names and standard numerals for whole numbers, fractions, decimals (through hundred-thousandths) and percents.

• MA.A.1.3.1.6.2 – reads and writes whole numbers and decimals in expanded form.

• MA.A.1.3.2.6.1 – compares and orders fractions and decimals using graphic models, number lines, and symbols.

Sunshine State Standards(http://www.floridastandards.org/Standards/FLStand

ardSearch.aspx

Your TurnQuestionArrange the prices of the CDs listed below

from greatest to least:$13.99 $14.09 $13.49 $13.4513.99

14.09

13.49

13.45

A) $13.45, $13.49, $13.99, $14.09

B) $13.45, $13.49, $13.99, $14.09

C) $14.09, $13.99, $13.45, $13.49

D) $14.09, $13.99, $13.49, $13.45

The prices of the CDs in order from greatest to least are $14.09, $13.99, $13.49, and $13.45.

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