Download 4. Fractions and decimals

-1-
GRADE 9 – FRACTION, DECIMAL, PERCENTAGE CONVERSIONS
CONVERTING COMMON FRACTIONS INTO DECIMAL FRACTIONS & VISE VERA
EXAMPLE
1
into a decimal fraction using a calculator: ________________________
5
1
 Convert
into a decimal fraction without using a calculator:
5
 Convert
 Convert 1,125 into a common fraction using a calculator: ____________________
 Convert 0, 3 into a common fraction using a calculator: ______________________
EXERCISE 2:
1.
Use your calculator to convert each of the following common fractions into decimals. Write
down all the decimal places displayed on the screen.
1.1
2
3
1.2
5
6
1.3
5
9
1.4
2
13
1.5
34
67
1.6
20
30
1.7
2
56
1.8
99
100
1.9
45
60
1.10
12
60
2.
Use your calculator to convert the following decimals fractions to fractions in their simplest
form:
2.1
0, 46
2.2
3, 69
2.3
9,12
2.4
0, 32
2.5
1, 2
2.6
0, 78
2.7
0, 85
2.8
1,14
2.9
5, 55
2.10
3, 22
3.1
Complete the following sequence:
0,1410 ; 0,1411 ; 0,1412 ; ______ ; _________ ; _______ ; 0,1416 ; ______ ; _________
-23.2
With the help of the sequence above, write down 3 rational numbers between 0,141 and
0,142.
_______________________________________________________________________________
3.3
Now write down 3 rational numbers between 0,1411 and 0,1412.
_______________________________________________________________________________
3.4
Write down 3 rational numbers between
5
6
and
.
10
10
_______________________________________________________________________________
3.5
Write down 3 rational numbers between
1
1
and .
4
2
_______________________________________________________________________________
CONVERTING BETWEEN FRACTIONS/DECIMALS AND PERCENTAGES
Remember that percentages are just fractions with a denominator of 100.
25% 
25
1
  0, 25
100 4
125% 
125
1
 1  1, 25
100
4
To convert a decimal number or fraction in a percentage, we simply multiply by 100.
EXERCISE 3:
1.
Write these percentages as fractions of 100:
1.1
73%__________
1.2
28%__________
1.3
10%__________
1.4
25%__________
2.
Write these fractions as percentages:
2.1
27
__________
100
2.2
3
__________
10
2.3
7
__________
50
2.4
1
___________
4
3.
Convert the following percentages to decimals:
3.1
39%
3.2
47%
3.3
83%
3.4
7%
3.5
2%
3.6
20%
-34.
Convert the following decimals to percentages:
4.1
0,31
4.2
0,67
4.3
0,09
4.4
0,05
4.5
0,2
4.6
0,75
5.
In a survey of 100 cars, 47 were white, 23 were blue and 30 were red Express each of these
numbers as a percentage of the total.
6.
7
of the surface of the earth is water. Express this as a percentage.
10
7.
There are 200 birds in a flock. 120 of them are female. What percentage of the flock are:
7.1
female
7.2
CONVERTING RECURRING DECIMALS TO FRACTIONS
..
e.g. 1) Convert 0, 6 to a decimal
Let x  0, 666666......
10 x  6, 666666......
9x  6
x 
6
9
x 
2
3
..
2) What about 0, 2 7 ?
See textbook for more examples
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