Transcript Introduction to Fractions

3
8
Introduction to Fractions
By Graeme Henchel
http://hench-maths.wikispaces.com
Index
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What is a fraction?
Mixed Numbers method 1
Mixed Numbers method 2
Equivalent Fractions
Special form of one Why
Special form of one
Finding equivalent fractions
Adding: Common denominators
Adding: Different denominators
Common denominators 1
Common denominators 2
½+1/3 with diagram
1/3+1/4 with diagram
½ +2/5 with diagram
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3/7+2/3 No diagram
Adding Mixed Numbers
Multiplying Fractions
Multiplying Mixed Numbers 1
Multiplying Mixed numbers 2
Multiplying Mixed diagram
Dividing Fractions
Fraction Flowchart .ppt
Fraction Flowchart .doc
Decimal Fractions
Fraction<->Decimal<-> %
What is a Fraction?
A fraction is formed by dividing a whole into a
number of parts
I’m the
NUMERATOR. I tell
you the number of
parts
2
3
I’m the
DENOMINATOR. I tell
you the name of part
Mixed numbers to improper fractions
1
2 
3
Convert whole numbers to thirds
Mixed number
1 6 1 7
2   
3 3 3 3
Improper fraction
Another Way to change Mixed
Numbers to improper fractions
2
3
5
In short
Since 5/5=1 there are
5x3+2=17
5 fifths
in each whole.
So 3 wholes will have
3x5=15 fifths.
Plus the 2 fifths
already there makes a
total of
15+2=17 fifths
17

5
Equivalent fractions
An equivalent fraction is one that
has the same value and position
on the number line but has a
different denominator
6
2
3
1



6
12
4
2
Equivalent fractions can be found by
multiplying by a special form of 1
2 3 4 5
1      ......etc..
2 3 4 5
Multiplying By a Special Form of One
Why does it work?
• Multiplying any number by 1 does not change
the value 4x1=4, 9x1=9 ……….
• Any number divided by itself =1.
2 3 4 5 6 7 8 9 10 11 12
1        


 ............
2 3 4 5 6 7 8 9 10 11 12
Multiplying a fraction by a special form of one
changes the numerator and the denominator but
DOES NOT CHANGE THE VALUE
8 25 2
8 25 2
3 17 10
3 17 10
9 6
9 6
20
20
5 125 4
5 125 4
7 50
11
11 7
50
Finding equivalent fractions
3
5
Convert 5ths to 20ths
?
20
3
4 of
so I must
multiply
by
WhatThat’s
do we 4multiply
5 by
to get a product
20?
5
4
3 4 12
 
5 4 20
Special form of 1
Simplifying Fractions: Cancelling
• Simplifying means finding an equivalent
fraction with the LOWEST denominator by
making a special form of 1 equal to 1
2
12
2 6 2
   1 
3
18
3 6 3
12 12  6
2


18 18  6
3
Another way
of doing this