Slide 1

http://www.mathsisfun.com/fractions_multiplication.html
Multiplying fractions is easy: you multiply the top
numbers(numerators) and multiply the bottom numbers(denominators).
For instance:

When possible, you reduce. In this case, however, nothing reduces,
because 8 and 45 have no factors in common. If you're not sure, you
can always do prime factorization:

Nothing cancels. Copyright ©
Often, though, something will cancel:

4 49 27


9 6 28

Put each number in prime-factored form and cancel common factors:

2 2 7 7 333
7




33 2 3 2 2 7
2

4 49 27



9 6 28

Another way…cancel common factors as you go..
1
1
2
3
7

1

4 49 27


9 6 28
3
1

4
2



7
2


Slide 2

Dividing fractions is just about as easy; there's just one extra
step. When you divide by a fraction, the first thing you do is
"flip-n-multiply". That is, you take the second fraction, flip it
upside-down, and multiply it by the first fraction. (The upsidedown fraction is called the reciprocal). For instance:
Example 1

5

5

6


5
6



5



5

1

6

5 1

5



1
5



1
6

Example 2:

5



6


2
3

5
6
2



31
2



22



4



1
4 5
4
1

1

1
4


Slide 3

Mixed Number - A number, such as 6 3
5

consisting of a whole number and a fraction. A mixed number is just the
sum of a whole number and a fraction.
Improper Fraction - A fraction in which the numerator is larger than the
denominator. Converting from mixed number to improper fraction:

6

3



5

6 5  3
5



33
5

Mixed numbers must be converted to improper fractions or decimals before
doing ANY MULTIPLICATION OR DIVISION OPERATIONS on them.
denominato

r numerator

A fraction can be converted into a decimal by dividing: Numerator ÷ Denominator

33

 33  5

5

6
5 33
 30
3

6

3
5


Slide 4

Example: What is 11/2 x 21/5 ?

Steps:
1.convert to Improper Fractions
2.Multiply the Fractions
3.convert the result back to Mixed Fractions

Example: What is 1 3/8 × 3 ?

= 11/8 × 3/1
= 33/8
= 4 1/8


Slide 5

http://www.mathsisfun.com/fractions_division.html


Slide 6

Area of a triangle

=height
=base

A= ½ x base x height

The height of a triangle is the distance from the top vertex (corner) to the bottom side.
If a triangle is a right triangle, the one of the sides could also be the height.

height= a

c
b =base