Transcript Fractions - Holy Rosary Website

During this topic you will learn to:
Understand the equivalence of fractions.
Simplify a fraction.
Change proper fractions to improper fractions.
Change improper to proper fractions
Add and Subtract fractions
Multiply and Divide fractions
1
2
2
6
2
8
49
98
2
5
4
12
5
15
4
6
3
9
8
16
30
75
2
4
3
12
19
76
1
4
4
10
14
35
25
75
9
18
3
7
4
8
25
70
33
99
5
9
Before we can look at adding fractions we
need to get some practice in finding
equivalent fractions.
So long as you multiply the top and the
bottom of a fraction by the same number
you will not change its size (because all you
are doing is multiplying by 1!)
e.g.,
2
5
x
This is just 1 whole
4
4
=
8
20
so
2
5
=
8
20
Match up the fraction on the left with its
equivalent on the right.
2
5
3
19
57
12
7
1
3
4
9
3
8
28
24
60
24
64
84
189
An improper fraction is one where the
numerator (top number) is bigger than the
denominator (bottom number).
This means that there must be more than
one whole one.
e.g.
=1
=
3
2
=
15
4
An improper fraction can also be
written as a mixed number. This means
a whole number and a fraction.
e.g.
=1
=
3
2
=
15
4
=1
1
2
=3
3
4
If you can find equivalent fractions then
simplifying fractions should not be a problem.
Give me some equivalent fractions for:
12
18
Which one do you think is the simplest and
why?
12
18
Simplifying a fraction just means finding an
equivalent fraction with the smallest numbers
possible
12
18
To convert an improper fraction into a mixed
number:
How many times does the denominator go
into the numerator ?
This is the whole number part.
The remainder is the numerator of the
fraction part.
Example:
38
=
9
4
2
9
How many times does 9 go into 38?
What is the remainder?
To convert a mixed number into an improper
fraction :
Multiply the whole number by the
denominator then add the numerator
This is the numerator of the improper
fraction
The denominator stays the same.
Example:
3
5
=
7
21
5
+
7
7
=
26
7
How many sevenths is 3 whole ones?
3 x 7 = 21
What do you think the answer to this is:
We can’t just add numerators and denominators or
we end up saying 2 halves make a half
1
2
+
1
2
=
2
4
=
1
2
We know that 2 halves make a whole one:
1
2
+
1
2
=
2
2
= 1
All we add are the numerators, the
denominator stays the same.
Before we can add fractions we have to
make sure the denominators are the same
This is where our equivalent fractions come
in:
2
5
+
3
6
We have to turn the thirds into sixths
2
3
+
5
6
=
4
6
+
5
6
=
9
6
This is the easiest operation to do with
fractions.
Just multiply the numerators to get the
numerator of the answer,
And multiply the denominators to get the
denominator of the answer.
e.g.
2
5
x
3
7
=
6
35
You can treat division just like multiplication
– there is just one step to do first.
Turn the fraction you are dividing by upside
down.
Then change the division to a multiplication.
e.g.
2
5

3
7
=
2
5
x
7
3
=
14
15