Finding a Percent of a Number

1
Finding a Percent of a Number
2
SPI 0606.2.6 Solve problems involving ratios,
rates and percents.
3
Definition of Percent

• Percent can be defined as a ratio that compares
  a number to 100 or per one hundred.

per
100
4
Percents Have Equivalents in Decimals and
Fractions
per
100
Do you know how to write 20 as a fraction and as
a decimal
5
20 Means
20 parts out of 100 or 20 hundredths.
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50
51 52 53 54 55 56 57 58 59 60
61 62 63 64 65 66 67 68 69 70
71 72 73 74 75 76 77 78 79 80
81 82 83 84 85 86 87 88 89 90
91 92 93 94 95 96 97 98 99 100
6
Percents Have Equivalents in Decimals and
Fractions
Fraction Simplified
Decimal
Fraction
Percent
20
.20



7
Copy the following slides into your notebook,
while your teacher reads them aloud to you!
8
How to Find the Percent of a Whole Number

• The first thing to remember is of means
  multiply in mathematics.

of
x

9
How to Find the Percent of a Whole Number

• Step 1 - When you see a percent problem you know
  when you read of in the problem you multiply.

x
25 of 200
10
How to Find the Percent of a Whole Number

• Step 2 Change your percent to a decimal and
  then move it two places to the left.

.
.
25 x 200
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How to Find the Percent of a Whole Number

• Step 3 Multiply just like a regular decimal
  multiplication problem.

200
x .
25
1000
400
5000
12
How to Find the Percent of a Whole Number

• Step 4 Place the decimal point 2 places to the
  left in your answer.

200
x .
25
1000
400
.
5000
13
What is the percent of this number?
.
20 of 820
.
x
820
x .
20
000
1640
.
16400
14
Your Turn ! See if you can solve the following
problems and then check your answers
15
What is the percent of this number?
.
x
40 of 725
.
2
1
725
x .
40
000
2900
.
29000
16
What is the percent of this number?
.
x
60 of 692
.
1
5
692
x .
60
000
4152
.
21520
17
Lets see how we will do with a word problem
18
On Saturday, Alma made 70 of the sales at a
store where she works. The total amount of sales
at the store on Saturday was 910. What was
Almas total amount of sales on Saturday?
19
What is the percent of this number?
910
x .
70
000
6370
.
63700
20
Outstanding Work!Your teacher will provide you
with a worksheet that includes additional
problems for you to solve