Transcript Fractions, Decimals and Percents

Fractions, Decimals and
Percents
Pre-Skill Check
Write each phrase as a decimal in numerical form.
1. Sixty-seven hundredths
0.67
2. Four and five tenths
4.5
3. Two hundred one and
fifty-three hundredths
201.53
4. Three hundred seventynine thousandths
0.379
5. Eight and four
hundredths
8.04
25
1. 0.25 = 100
Ones
.
Tenths
Hundredths
Decimals to fractions
75
Ex: 4
4.75
75 = 4100
 Any number to the left of
the decimal is a whole
number.
 The number to the right
5
4. 3.05 = 3100
of the decimal is the
numerator of the fraction.
7
5. 2.007 = 2 1000
 The place value of the
92
6. 271.092 = 2711000 LAST digit in the number
is the denominator.
2. 2.3 = 2 3
10
609
3. 70.609 = 70 1000
Fractions to Decimals
6
4
= 4 + 0.66 = 4.66
Ex:
9
Any whole
number is a
number to
the left of
the decimal.
Divide the
denominator
into the
numerator.

0 .6 6
96 .0 0
- 54
60
- 54
6
1.
7 = 0.7
10
2.
2 = 0.22
9
5 = 0.714…
7
3 = 0.375
8
3 = 2.75
24
4 = 36.8
36 5
3.
4.
5.
6.
Decimals to Percents
0.97 = 97%
0.60 = 60%
Turn the Decimals into
 Move the decimal
Percents
to the right 2
1. 0.56 = 56%
places.
2. 0.79 = 79%
 If there are not
3. 0.05 = 5%
enough numbers to
fill the spaces add a 4. 0.2 = 20%
5. 0.367 = 36.7%
‘0’ to fill it in.
6. 2.1 = 210%
Warm Up - 2/4/09
Turn the decimals into
fractions.
1. 3.65 = 3 65
100
2. 0.73 = 73
100
3. 19.087 = 19 87
1000
Turn the Decimals into
Percents.
4. 0.71 = 71%
5. 0.3 = 30%
6. 0.08 = 8%
7. 0.276 = 27.6% or 28%
Percents to Decimals
32% = 0.32
0 1% = 0.01
Turn the Percents into
 Move the decimal
Decimals
to the left 2 places. 1. 75% = 0.75
 If there are not
2. 24% = 0.24
enough numbers to
3. 3% = 0.03
fill the spaces add a
4. 10% = 0.1 or 0.10
‘0’ to fill it in.
5. 12.6% = 0.126
6. 150% = 1.5 or 1.50
Fractions and Percents
Fractions to Percents
 First turn the
fractions into
decimals.
 Then follow the
process for turning
Decimals into
Percents.
Percents to Fractions
 First turn the percent
into a decimal.
 Then turn the
decimal into a
fraction.
Fractions and Percents
Turn the Fractions into
percents.
1.
2.
3.
4.
3
10
4
5
9
11
2
4
= 0.3
Turn the Percents into
Fractions.
5. 25% = 0.25 = 25
100
= 30% 6. 75% = 0.75 = 75
100
33
7.
33%
=
0.33
=
= 0.8 = 80%
100
8. 2% = 0.02 = 2
100
= 0.818 = 82%
9. 4% = 0.04 = 4
= 0.5
100
5 or 50
= 50% 10. 50% = 0.5 = 10
100
Taking a Percent of an
the percent into
Amount. Turn
a decimal and then
Khadijah went to
a sale at her
favorite store.
She found a
jacket that was
20% off. If the
original cost of
the jacket was
$150. How much
money will she
save?
multiply the decimal
by the amount.
20% of 150
1
20% = 0.20
150
150 x 0.20 = 30
x0
0.20
20
0 00
3 00 0
She would save $30.
+00 0 00
0 3 0 00
How much will the jacket cost?
$150 - $30 = $120
Warm Up – 2/5/09
Bestbuy is having a sale. You found the CD
you wanted for 30% off. The original cost was
$17.95. What is the sale cost of the CD before
taxes?
How much will the CD cost?
30% of 17.95
30% = 0.30
$17.95 - $5.39 = $12.56
17.95 x 0.30 = 5.39
You would save $5.39.
2 21
17.95
x0
0.30
30
0 0 00
5 3 85 0
+ 0 0 0 0 00
05 3 8 50
Find the percent of each
amount.
Show your Work.
1. 25% of 80
= 20
2. 33% of 90
= 29.7
3. 40% of 67
= 26.8
4. 65% of 175 = 113.75
Topics Covered So far
 Decimals to Fractions
 Fractions to Decimals
 Decimals to Percent
 Percent to Decimals
 Fractions to Percents
 Percents to Fractions
 Percent of an amount
Percents
Target is having a sale on movies. Chris found
the movie he wanted at a discounted price. He
saved $8 off the original price of $25. What
percent of the original price did he save?
What are we looking for?
The percent off.
How do we find that?
First lets look at another problem and
come back to this one later.
Percents
If Chris found the movie for 20% off and the
original cost was $25. How much would he
save?
Remember that 0.20 is the
20% of $25
20% = 0.20
25 x 0.20 = 5.00
He would save $5.00.
same as 0.2
To make the multiplication
easier use 0.2
1
25
x0
0.2
2
50
Percents
Back to our original problem.
Target is having a sale on movies. Chris found
the movie he wanted at a discounted price. He
saved $8 off the original price of $25. What
percent of the original price did he save?
What are we looking for?
The percent off.
How do we find that?
Percents
When we wanted to
find the amount of
the discount we
multiplied the
percent off by the
original cost.
20% of $25
20% = 0.20
25 x 0.20 = 5.00
You would save $5.00.
So to find the
percent of the
discount we do the
opposite.
What % = 8
25 x ______
If 25 x something = 8 then
8÷25 = that same something
For ex: 6 x 4 = 24
so: 24÷6 =44
Percents
To find the percent of an
amount when you know the
original cost and the amount
of the discount. Divide the
discount by the original cost.
So to find the
percent of the
discount we
do the
opposite.
0 .3 2
What % = 8
25 x ______
If 25 x something = 8 then
8 /25 = that same something
For ex: 6 x 4 = 24
so: 24/6 = 4

258.0 0
- 75
50
- 50
0
Percents
8/25 = 0.32
0.32 = 32%
So, he is saving 32% off the cost of the movie.
Find the percent of the
number
1.
2.
3.
4.
5.
7 is what percent of
35?
12 is what percent of
60?
50 is what percent of
75?
42 is what percent of
84?
6 is what percent of
32?
20%
20%
66.7% or 67%
50%
18.7% or 19%
Taking a Percent of an
Turn the percent into
Amount. a decimal and then
multiply the decimal
by the amount.
35% of 49.99
2 22
4 44
35% = 0.35
49.99
49.99 x 0.35 = 17.50
x0
0.35
35
1 1 1
2 4 9 95
14 9 9 7 0
He would save $17.50. + 0 0 0 0 00
17 4 9 65
Michael went to
buy a new video
game for his
Xbox 360. He
found the game
he wanted on
sale for 35% off.
The original cost How much will the game cost?
was $49.99.
What is the sale
$49.99 - $17.50 = $32.49
cost of the game
before taxes?
Warm Up – 2/6/09
Turn the percents into
fractions.
1. 79% = 0.79 = 79
100
2. 12% = 0.12 = 12
100
3. 56% = 0.56 = 56
100
Turn the Decimals into
Percents.
4. 2.51 = 251%
5. 0.07 = 7%
70%
6. 0.7 =
7. 0.329 = 32.9% or 33%