STRAND: Number
TOPIC:
Percentages
Changing fractions to
equivalent fractions with a
denominator of 100
To change a fraction into an equivalent fraction with a denominator of 100:
1. establish how many times the given denominator fits (divides) into 100
2. multiply both the numerator and the denominator by that number.
Remember that factor pairs of 100 could be of assistance. These are 1 and 100, 2 and 50, 4 and 25, 5 and 20 and 10 and 10.
So if the given denominator is one factor in a pair, then both the numerator and the denominator must be multiplied by the other
factor in that pair. For example, if the given denominator is 20, the numerator and the denominator must be multiplied by 5.
WORKED Example
Change
3
--5
into an equivalent fraction with a denominator of 100.
THINK
WRITE
The denominator of the given fraction (that is, 5)
fits into 100 twenty times. So multiply both
numerator and denominator by 20.
3
--5
=
=
3 × 20
--------------5 × 20
60
--------100
Try these
Change each of the following into equivalent fractions with a denominator of 100.
1
1
--5
2
4
--5
3
3
-----10
4
7
-----10
5
6
3
--4
7
3
-----20
8
17
-----20
9
8
-----25
10
1
--2
39
-----50
 John Wiley & Sons Australia, Ltd 2001