Transcript Fractions

Fractions
• Simplifying
• Equivalences
Equivalent Fractions of one half
1 5
7 4 20 8


 

2 10 14 8 40 16
The bottom number is twice the top number
The top number is half the bottom number
In a fraction the top number is the
numerator. The bottom number is
the denominator.
Which of these fractions are equivalent to a half.
Look at the relationship between the numerator and the denominator.
8
12
8x2=16 so no
11
It is relatively easy
to see ifsoa yes
11x2=22
22equals a half or not.
fraction
15
30
15x2= 30 so yes
Which of these are equivalent to a
third?
Is the bottom number three times the
top number?
2
5
2
6
3
9
10
30
No
Yes
Yes
Yes
100
300
9
12
7
21
Yes
No
Yes
Simplifying fractions –
a general method
You have to find a common divisor –
a number which will go into both the top
number and the bottom number and leave
no remainder
Find a number that will go into the
numerator and denominator and
leave no remainder
25
100
What number will go into 25 and 100 and leave no remainder?
5 is a possibility
25
5

100 20
What number will go into 5 and 20 and leave no remainder?
25
5 1


100 20 4
5 is a possibility again
We can’t go any further
Find a number that will go into the
numerator and denominator and
leave no remainder
28
42
28 14

42 21
What number will go into 28 and 42 and leave no remainder?
They are both even numbers so two will work
What number will go into 14 and 21 and leave no remainder?
28 14 2


42 21 3
7 will
We can’t go any further
Simplifying fractions- You need to
know your times tables
Even numbers end in 0, 2, 4, 6, 8 –
Two will always go into and even number.
Here are some even numbers
32
74
18
96
110
Simplifying fractions- You need to
know your times tables
To see if 3 goes into a number – see if three
goes into the sum of the digits –
example - 39 (3+9=12=3x4)
Here are some numbers that are divisible by
three
51
5+1=6=3x2
63
6+3=9=3x3
108
48
1+0+8=9=3x3
4+8=12=3x4
Simplifying fractions- You need to
know your times tables
Five will go into any number that ends in zero or
five
Ten will go into any number that ends in zero
Twenty five will go into any number that ends in
00, 25, 50, 75
Try to simplify these fractions
18 6 2 35  7
 
63 21 7 60 12
44 4

77 7
60
35
12
5
 1
7
12
5
125

300 12
82 41 1
 2
40 20 20