PERCENTAGES

1
PERCENTAGES
2
Introduction

• Meaning
• Percentage as a fraction
• Percentage as a decimal
• Percentages of amount without a calculator
• Percentages of amount with a calculator

3
MEANING

• Per centum is a Latin word which means by the
  hundred
• Percent means per hundred or out of a hundred
• Percent is written using the symbol

4
Percentage as a fraction
Write the percentage figure down without the
symbol
Put a line under this figure
Write the number 100 under this line
Try to simplify the fraction you have now written
by dividing the top and bottom line numbers by
the same figure
5
WORKED EXAMPLES
2. 54
1. 21
54
21
100
100
27
50
6
WHAT GOES IN THE BOXChange the following
percentages to fractions
5. 47 6. 91

• 1. 13 2. 59

47
91
13
59
100
100
100
100
3. 37 4. 71
7. 29 8. 63
63
37
71
29
100
100
100
100
7
WHAT GOES IN THE BOXChange the following
percentages to fractions



3. 18
2. 44
4. 25
1. 30

30
44
18
25
100
100
100
100
1
3
11
9
10
4
25
50
8
Percentage as a decimal
Write the percentage figure down without the
symbol
Write down the division symbol followed by 100
Divide
Write down the answer
9
WORKED EXAMPLES

1. 7
7
100
0.07
2. 38
100
0.38
38
10
WHAT GOES IN THE BOXChange the
following percentages to decimals
1. 4
4. 7



100
0.04

7
0.07

4

100

2. 37
5. 19.2
0.192



100
100
0.37

19.2


37
3. 98
6. 0.83

0.83




100
98
0.98

0.0083
100
11
Percentage of amount without a calculator
(method 1 )
Write down 100 Amount
Divide both sides of equals sign by 10 to find 10
Divide both sides of equals sign by 10 again to
find 1
Dividing 100 by 2 will give 50
Dividing 10 by 2 will give 5. Dividing 10 by 5
will give 2
By combining values for 50 , 10 , 5 2 and
1 then adding find the value of percentage
figure required
12
WORKED EXAMPLES
1. Find 20 of 130
10 13 10 13 20 26
100 130

10 13
1 1.30
2. Find 75 of 48 ml
50 24 ml
100 48 ml
10 4.8 ml
50 24 ml
10 4.8 ml
10 4.8 ml
5 2.4 ml
5 2.4 grams
75 36.0 ml
13
What goes in the box
1. Find 15 of 270

10 27

100 270

5 13.50

10 27
15 40.50

5 13.50
2. Find 72 of 58 cm
50 29 cm

100 58 cm

10 5.8 cm
50 29 cm
10 5.8 cm
10 5.8 cm
2 1.16 cm

2 1.16 cm

72 41.76 cm
14
Percentage of amount without a calculator (method
2 )
Change the percentage to a fraction
Write down the fraction x amount
Divide amount by the bottom line number of the
fraction
Now multiply this answer by the top line
number of the fraction and write down the answer
15
WORKED EXAMPLES
1. Find 20 of 120

20
20 100
1 5
120 5 24
1 X 120 5
24 X 1 24
2. Find 75 of 84 grams
75
75 100
3 4
3 X 84 g 4
84 4 21 g
21 X 3 63 g
16
WHAT GOES IN THE BOX
1. Find 25 of 248

25
25
1
100
4
1

248 4 62
62 x 1 62
X 248
4
2. Find 30 of 70 grams
30
3



30
100
10
7 x 3 21 g
3
70 10 7 g

X 70
10
17
Percentage of amount with a calculator
Change the percentage to a decimal
Write down the decimal x amount
Now use a calculator to find this answer then
write it down
18
WORKED EXAMPLES
1. Find 42 of 310
42
42 100
0.42
0.42 x 310
130.20
2. Find 7 of 93 grams

7
7 100
0.07
0.07 x 93 g
6.51 g
19
What goes in the box
1. Find 24 of 130

24

24 100
0.24
0.24 x 130
31.20

2. Find 9 of 67 grams

9
9 100
0.09
0.09 x 67 g
6.03 g