Transcript Decimals - LearningSheets

DECIMALS
Reading & Writing
Decimals
Decimal Place Values
Lets take a look at the places and the values of decimals.
Tens
Ones
10
1
Tenths
.
Decimal
.1
Hundredths Thousandths
.01
.001
Example
8,243.67
Eight thousand, two hundred forty-three
“and”sixty-seven hundredths
Lets Practice:
 247.017
two hundred forty-seven and seventeen thousandths
 16.3
sixteen and three tenths
 4,764.52
Four thousand, seven hundred sixty-four and fifty-two hundredths
63,920.143
Sixty-three thousand, nine hundred twenty and
.
one hundred forty-three thousandths
Writing Decimals in
Standard Form
Example: Write the following number in
standard form:
two hundred six and five thousandths
5
206 . __
0 __
0 __
The word “thousandths” indicates that we need three decimal places.
When we clean it up, the answer is 206.005
Lets Practice:
 Six hundred fifty-three and twenty-three
hundredths
653.23
Fourteen and five tenths
14.5
Three thousand, nine hundred thirty-five and
sixty-one thousandths
3,935 .061
Writing Decimals
in Expanded Form
Example: Write 13.361 in expanded
form.
Remember, deal with the number before the decimal first.
10 + 3 + 0.3 + 0.06 + 0.001
Then, do the decimal part.
Lets Practice:
 249.617
200 + 40 + 9 + 0.6 + 0.01 + 0.007
 16.3
10 + 6 + 0.3
 4,764.52
4,000 + 700 + 60 + 7 + 0.5 + 0.02
.
Lets Practice:
200 + 40 + 9 + 0.6 + 0.01 + 0.007
249.617
10 + 6 + 0.3
16.3
4,000 + 700 + 60 + 7 + 0.5 + 0.02
4,764.52
Special Seatwork
(6 points)
Write these in words.
1.) 35.037
2.) 10.238
3.) 8.009
Special Seatwork
(6 points)
Write these in standard decimal
form.
1.) forty-five and two thousandths
2.) four and nine hundredths
3.) six and twenty-one hundredths
Special Seatwork
(6 points)
Write these in expanded form.
1.) 4.205
2.) 10.871
3.)25.084
Games on decimals
Workbook
Exercise A
Number 1 to 6
Page 63 to 65
Digit Value
Example
12.0945
Digit value of
1 – 10
2–2
0–0
9 – 0.09
4 – 0.004
5 – 0.0005
Exercise
From the number 2.4079, find
the digit value of the
following;
a.) 2 - ________
b.) 4 - ________
c.) 0 - ________
d.) 7 - ________
e.) 9 - ________
Special Seatwork (3 points)
From the number 32.508, find
the digit value of the
following;
a.) 3 - ________
b.) 2 - ________
c.) 5 - ________
d.) 0 - ________
e.) 8 - ________
Workbook
Exercise B
Number 1 to 4
Page 66 to 67
Comparing Decimals
Example 1
Which is bigger 10.408 or 10.508?
Answer:
Since 5 is bigger than 4 on the
tenths place, therefore 10.508 is
bigger than 10.408.
Example 2
Which is smaller 8.347 or 8.346?
Answer:
Since 6 is smaller than 7 on the
thousandths place, therefore 8.346
is smaller than 8.347.
Exercise
1.) Which is larger 26.357 or 26.358?
2.) Which is the largest 3.74, 3.78 or
3.71?
Special Seatwork( 3 points)
1.) Which is smaller 0.047 or 0.329?
2.) Which is larger 139.0047 or
128.9059?
Special Seatwork( 3 points)
1.) Which is smallest 10.147, 10.329,
12.025 or 11.013?
2.) Which is largest 9.3044, 9.3324
8.5039 or 9.434?
Workbook
Exercise C
Number 1 to 6
Page 68 to 69
CONVERTING DECIMALS TO FRACTIONS
Example 1
Convert 2.8 to fraction.
Working:
2.8 = 2 + 0.8
= 2 + 8/10
= 2 + 4/5
4
= 2 /5
Example 2
Convert 45.3 to fraction.
Working:
45.3 = 45 + 0.3
= 45 + 3/10
= 45 + 3/10
3
= 45 /10
Exercise
Convert the following to
fractions.
1.) 4.25
2.) 12.8
3.) 9.7
Special Seatwork ( 3 points)
Convert the following to
fractions.
1.) 6.14
2.) 24.6
3.) 3.3
CONVERTING FRACTIONS TO DECIMALS
Example 1
Convert 3 2/5 to decimals.
Working:
3 2/5 = 3 + 2/5
= 3 + 2/5 x 2/2
= 3 + 4/10
= 3 + 0.4
= 3.4
Example 2
Convert 2 8/25 to decimal.
Working:
2 8/25 = 2 + 8/25
= 2 + 8/25 x 4/4
= 2 + 32/100
= 2 + 0.32
= 2.32
Exercise
Convert the following to
decimals.
1.) 6/10
2.) 2 4/10
3.) 1 4/5
Special Seatwork ( 3 points)
Convert the following to
decimals.
1.) 2 1/2
2.) 14/5
3.) 3/5
Workbook
Exercise D
Number 1 to 4
Page 70 to 71
OPERATIONS
WITH
DECIMALS
ADDITION OF DECIMALS
Vertical Addition
Examples
1.) 12.6 + 9.7 =
Working
12.6
9.7
22.3
2.) 42.653 + 3.9057 =
Working
42.6530
3.9057
46.5587
3.) 46.4054 + 9.63 =
Working
46.4054
9.6300
56.0354
Workbook
Exercise A
Number 1 to 6
Page 75 to 77
SUBTRACTION OF DECIMALS
Vertical Subtraction
Examples
1.) 12.9 - 9.7 =
Working
12.9
9.7
3.2
2.) 42.658 - 3.9057 =
Working
42.6580
3.9057
38.7523
Workbook
Exercise B
Number 1 to 6
Page 78 to 80
MULTIPLICATION OF DECIMALS
Vertical Multiplication
Examples
1.) 5 x 0.8 =
Working
5
x 0.8
4.0 or 4
Examples
2.) 4 x 1.7 =
Working
4
x 1.7
28
4_
6.8
More Examples on the board
Workbook
Exercise C
Number 1 to 5
Page 81 to 83
Solving word problems with
decimals
Workbook exercise D letter A
Page 84.
A boy had 345.25 Baht.
He bought a wallet for
256.50 Baht. How much
money did he have left?
We UNDERSTAND
Question: How much money did he have left?
Given: A boy had 345.25 Baht and he bought a
wallet for 256.50 Baht.
We PLAN
Key words: left
Operation: Subtraction
We SOLVE
Number Sentence: 345.25 – 256.50 = ____
Working:
345.25
256.50
88.75
We CHECK
By Addition
88.75 + 256.50 = 345.25
345.25 = 345.25
Therefore, 88.75 is a correct answer.
Answer:
He have left 88.75 Baht.
Workbook
Exercise D
Letter B to D
Page 85 to 87
(By Group)
Creating Word Problems with
Decimals
Workbook
Exercise E
Letter A and B
Page 88
Solving Mixed Operations with
Decimals
Examples
Workbook
Exercise E
Letter A and B
Page 88
Workbook
Exercise F
Number 1, 2 and 3
Page 89 to 90