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Shortcut to multiply fractions. Students may choose to work multiplication problems with this method to shorten the time needed to work the problem.
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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