Transcript Decimals & Place Value

Decimals and Place
Value & Comparing
Decimals
Lessons 3.1 & 3.3
Decimals & Place Value
• Where do you see decimals?
Money
Times (races)
Scores
• We will look at how to write
decimal amounts in words,
numbers, or using models.
Decimals & Place Value
Place Value Chart
Hundred-thousandths
Ten-thousandths
Thousandths
Hundredths
Tenths
Hundred thousands
Ten-thousands
Thousands
Hundreds
Tens
Ones
.
Decimals & Place Value
Example 1 – Write the following
amount in word form.
Lowest place value?
18.021
thousandths
Eighteen and twenty-one
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 2
Compare the following numbers:
< 71.354
71.264 ___
A. >
71.264
B. <
71.354
C. =
71.2
71.25
71.3
71.35
Your Turn
Question #3
Allison has $125.08. Greg has $125.06.
Compare the two amounts of money.
Who has the most money?
125.08
A. Allison
125.06
B. Greg
Allison has the most money.
Your Turn
Question #4
Compare the following numbers:
123.18 ____ 123.1800
A. >
B. <
C. =
123.18
123.1800
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 Decimals
Example 3
Order the following numbers from least to
greatest:
9.41 9.399 9.4102
9.4110
9.4100
2
9.3990
1
9.4102
3
9.4110
4
The order of the numbers from least to greatest is
9.399, 9.41, 9.4102, 9.4110
Your Turn
Question #5
A 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
B) Team
C) Team
D) Team
A, Team B, Team C, Team D
B, Team C, Team A, Team D
C, Team A, Team D, Team B
D, Team B, Team A, Team C
Your Turn
Question #5 (procedure to follow)
Team A 94.175 2
Team B 94.050 4
Team C 96.350 1
Team D 94.150 3
96.35 (Team C), 94.175 (Team A), 94.15 (Team
D), 94.05 (Team B)
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
Sunshine State Standards
(http://www.floridastandards.org/Standards/FLStandardSearch.aspx
• MA.A.1.3.1.6.1 – knows word names and standard numerals for
whole numbers, fractions, decimals (through hundredthousandths) 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.
Your Turn
Question
Arrange the prices of the CDs listed below
from greatest to least:
$13.99 $14.09 $13.49 $13.45
2
14.09 1
13.49 3
13.45 4
13.99
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.