multiply fractions shortcut

Multiplying Fractions

Goals: I can figure out how to solve multiplication problems with fractions in real-world situations.

Standard: MCC5.NF.6: Solve real world problems involving multiplication of fractions and mixed numbers, e.g., by using visual fraction models or equations to represent the problem.

Credits: Special thanks to Kelly Katz, for some of the slides in this presentation.

Shortcut Method

Warning:

This method will not work with every multiplication

problem. Be prepared to at all times to multiply large number & simplify large

numbers.

Shortcut Method

_5_12

_6_10

1 1

22

Shortcut Method

_5_12

_6_10

1 1

22

= 14

Shortcut Method

_3_7

_2_5

Shortcut Method

_3_7

_2_5

=6

35

Shortcut Method

_4_6

_3_4

1 1

12

Shortcut Method

_4_6

_3_4

1 1

12

= 12

Shortcut Method

136

_1_4

Shortcut Method

136

_1_4

=1324

Shortcut Method

208

_4_4

5 1

12

Shortcut Method

20 8

4_4

5 1

12

= 52

What is wrong with this answer?

52

Improper Fraction Proper Fraction

Which type of

fraction is it?

Improper Fraction → Mixed Number

1. Divide the numerator by the denominator

2. Put the remainder over the denominator

=52

522

41

R 1Divide the

numerator by the denominator

Write the remainder

over thedenominator

2

2 12

Convert the improper fraction to a Convert the improper fraction to a mixed number:mixed number:

73

132

Convert the improper fraction to a Convert the improper fraction to a mixed number:mixed number:

83

232

Convert the improper fraction to a Convert the improper fraction to a mixed number:mixed number:

92

124

Convert the improper fraction to a Convert the improper fraction to a mixed number:mixed number:

115

152

Convert the improper fraction to a Convert the improper fraction to a mixed number:mixed number:

105 2

If there is no remainder then your answer is

a whole number!

Name: __________________ Date: ____________________ Group: _____

I can: demonstrate my knowledge of multiplying fractions!

Multiply these fractions (using Shortcut Method)!

1. 5 x 4 = 2. 3 x 7 = 8 10 6 9

Multiply (using Shortcut Method) these fractions and turn your answers into mixed numbers! Don’t forget to simplify!

3. 2 x 18 = 4. 8 x 27 = 5. 12 x 4 = 3 10 9 2 3

Simplify these Fractions!

6. 12 = 7. 6 = 24 18

8. Cody has 27 marbles. Five-Ninths of the marbles are purple. How many marbles are purple?_______ are purple

9. How many are not purple? _______ are not purple